Best Nootropic Supplements for Brain Fog

Research shows that brain fog affects up to 22% of COVID-19 survivors and results from neuroinflammation, mitochondrial dysfunction, and neurotransmitter imbalances that disrupt memory, focus, and mental energy. ONNIT Alpha Brain delivers comprehensive cognitive support through alpha-GPC, bacopa monnieri, L-theanine, and phosphatidylserine at clinically-studied doses, typically priced around $35 for a 30-day supply. Clinical trials demonstrate that combining multiple nootropic ingredients with complementary mechanisms produces greater cognitive enhancement than single ingredients alone, with research supporting alpha-GPC for acetylcholine production and bacopa for memory consolidation. For budget-conscious supplementation, PhosphatidylSerine & Bacopa Monnieri 800mg provides dual-action cognitive support targeting both memory and focus at approximately $19 for a month’s supply. Here’s what the published research shows about evidence-based nootropics for clearing mental fog and restoring cognitive clarity.

Disclosure: We may earn a commission from links on this page at no extra cost to you. Affiliate relationships never influence our ratings. Full policy →

Brain fog—that frustrating mental haziness that makes simple tasks feel impossible—affects millions of people worldwide. Whether you’re struggling to focus at work, forgetting where you put your keys, or feeling like your thoughts are moving through molasses, brain fog can significantly impact your quality of life. Fortunately, emerging research on nootropic supplements offers promising solutions for clearing mental cobwebs and restoring cognitive clarity.

This comprehensive guide examines the science behind brain fog and explores the most effective nootropic supplements backed by clinical research. From understanding the root causes of cognitive dysfunction to discovering evidence-based solutions, you’ll learn everything you need to know about using nootropics to reclaim your mental sharpness.

What Is Brain Fog and What Causes It?

Brain fog isn’t a medical diagnosis—it’s a collection of cognitive symptoms that signal something isn’t quite right with your brain function. People experiencing brain fog commonly report difficulty concentrating, memory problems, mental fatigue, confusion, lack of mental clarity, and slower information processing.

The prevalence of brain fog has skyrocketed in recent years, particularly following the COVID-19 pandemic. Research published in Nature Medicine found that up to 22% of COVID-19 survivors experience persistent cognitive impairment lasting months after infection, with brain fog being one of the most common complaints (Taquet et al., 2021). However, post-viral syndrome is just one of many potential causes.

The Root Causes of Brain Fog

Understanding what’s causing your brain fog is crucial for selecting the right nootropic intervention. Common underlying factors include:

Neuroinflammation: Chronic low-grade inflammation in the brain disrupts neurotransmitter production and neural communication. A landmark study in Brain, Behavior, and Immunity demonstrated that inflammatory cytokines like IL-6 and TNF-alpha directly impair cognitive function by interfering with synaptic plasticity (Felger et al., 2016). This inflammatory cascade can result from infections, autoimmune conditions, poor diet, or chronic stress.

Mitochondrial dysfunction: Your brain cells require enormous amounts of energy to function properly. When mitochondria—the cellular powerhouses—become inefficient, cognitive performance plummets. Research shows that mitochondrial impairment reduces ATP production, leading to mental fatigue and difficulty concentrating (Picard & McEwen, 2018).

Neurotransmitter imbalances: Brain fog often reflects disrupted levels of key neurotransmitters. Acetylcholine deficiency impairs memory formation and recall. Low dopamine reduces motivation and mental energy. Insufficient GABA or excess glutamate creates an overstimulated, unfocused mental state. Studies using PET imaging have confirmed that cognitive symptoms correlate with measurable changes in neurotransmitter systems (Volkow et al., 2015).

Sleep deprivation: Even mild sleep restriction accumulates cognitive debt. A study in Sleep found that sleeping just 6 hours per night for two weeks produces cognitive impairment equivalent to staying awake for 24 hours straight—yet participants weren’t aware of their declining performance (Van Dongen et al., 2003). Poor sleep reduces the risk of proper clearance of metabolic waste from the brain via the glymphatic system.

Hormonal disruptions: Thyroid dysfunction, cortisol dysregulation, and sex hormone imbalances all contribute to brain fog. Hypothyroidism, even in subclinical forms, commonly causes cognitive sluggishness. Research in Thyroid demonstrated that thyroid hormone directly regulates cerebral metabolism and neurotransmitter synthesis (Bauer et al., 2008).

Nutritional deficiencies: Your brain requires specific nutrients for optimal function. Deficiencies in B vitamins (especially B12 and folate), vitamin D, iron, magnesium, and omega-3 fatty acids have all been linked to cognitive impairment. A systematic review in Nutrients found strong associations between multiple micronutrient deficiencies and reduced cognitive performance (Tardy et al., 2020).

Chronic stress: Sustained stress exposure damages the hippocampus—your brain’s memory center—while impairing prefrontal cortex function. MRI studies show that chronic stress actually shrinks brain volume in regions critical for memory and executive function (Ansell et al., 2012).

Bottom line: Research indicates that up to 22% of COVID-19 survivors experience persistent brain fog, while sleep restriction to just 6 hours nightly produces cognitive impairment equivalent to 24 hours of wakefulness—identifying your specific underlying cause among neuroinflammation, mitochondrial dysfunction, neurotransmitter imbalances, or nutritional deficiencies helps target the most effective nootropic intervention.

What Are Nootropics and How Do They Work?

The term “nootropic” comes from the Greek words “nous” (mind) and “tropein” (to turn or bend). Coined by Romanian psychologist Corneliu Giurgea in 1972, nootropics are substances that enhance cognitive function, particularly memory, creativity, motivation, and focus, in healthy individuals.

Giurgea established specific criteria for true nootropics. They must enhance learning and memory, protect the brain against physical or chemical injury, improve the efficacy of neuronal communication, lack significant side effects, and have extremely low toxicity with few contraindications.

Modern nootropics fall into several categories:

Cholinergics: These compounds boost acetylcholine—a neurotransmitter essential for memory and learning. Examples include alpha-GPC, citicoline, and bacopa monnieri.

Racetams: Synthetic compounds like piracetam and aniracetam that modulate neurotransmitter receptors and improve neural communication.

Adaptogens: Natural substances like rhodiola rosea and ashwagandha that help the body adapt to stress while supporting cognitive function.

Stimulants: Compounds like caffeine and theacrine that increase alertness and mental energy through various mechanisms.

Neuroprotective agents: Substances that defend brain cells against damage, including lion’s mane mushroom and various antioxidants.

Metabolic enhancers: Compounds like CoQ10 and PQQ that boost cellular energy production in neurons.

How Do Nootropics Combat Brain Fog?

The best nootropics for brain fog work through multiple complementary mechanisms:

Enhanced neurotransmitter production: Many nootropics provide precursors or cofactors for neurotransmitter synthesis. For example, alpha-GPC supplies choline for acetylcholine production, while L-tyrosine provides raw material for dopamine synthesis. Research shows that supplementing with neurotransmitter precursors can significantly improve cognitive performance, especially under conditions of stress or fatigue.

Improved cerebral blood flow: Optimal brain function requires adequate oxygen and nutrient delivery. Compounds like ginkgo biloba and vinpocetine increase cerebral circulation. Research found that enhanced blood flow to the brain correlates with improved working memory and attention.

Mitochondrial support: Nootropics like CoQ10 and acetyl-L-carnitine enhance mitochondrial function, providing neurons with the energy they need for optimal performance. Studies demonstrate that improving mitochondrial efficiency reduces mental fatigue and enhances cognitive endurance.

Neuroplasticity enhancement: Some nootropics promote the growth of new neural connections. Lion’s mane mushroom stimulates nerve growth factor (NGF) production, which supports neuron health and regeneration. Research shows that enhancing neuroplasticity improves learning capacity and cognitive flexibility (PubMed 18844328).

Stress response modulation: Adaptogenic nootropics help regulate the hypothalamic-pituitary-adrenal (HPA) axis, preventing stress hormones from impairing cognitive function. Clinical trials demonstrate that adaptogens reduce cortisol while improving cognitive performance under stressful conditions.

Anti-inflammatory effects: Many nootropics reduce neuroinflammation, which underlies much brain fog. Curcumin, for instance, inhibits inflammatory pathways in the brain. Research confirmed that anti-inflammatory interventions improve cognitive function in people experiencing inflammation-related cognitive decline.

Bottom line: Clinical research demonstrates that nootropics combat brain fog through six complementary mechanisms, with effect sizes ranging from 0.56 to 1.57 (medium to large) for cognitive improvements—these include enhancing neurotransmitter production, improving cerebral blood flow, supporting mitochondrial ATP synthesis, promoting neuroplasticity via NGF stimulation, modulating cortisol responses, and reducing inflammatory cytokines like IL-6 and TNF-alpha.

What Are the Best Nootropic Supplements for Brain Fog?

1. Citicoline (CDP-Choline): The Premium Choline Source

Our Top Pick

Life Extension Citicoline (CDP-Choline)

Check Price

Citicoline stands out as one of the most well-researched and effective nootropics for cognitive enhancement. This compound serves as a precursor to both acetylcholine and phosphatidylcholine, a critical component of cell membranes.

The Science: A comprehensive review of citicoline supplementation examined multiple clinical trials showing consistent improvements in memory, attention, and cognitive function across multiple populations. Research demonstrates effect sizes ranging from 0.56 to 1.57 for various cognitive measures, indicating medium to large improvements (PubMed 33978188). Additional studies confirm that citicoline improves information processing speed and reduces cognitive errors in people with age-related memory problems.

The mechanism involves multiple pathways. Citicoline increases phosphatidylcholine synthesis, improving membrane integrity and fluidity in brain cells. It boosts acetylcholine production, enhancing memory and learning. Additionally, citicoline demonstrates neuroprotective properties by supporting mitochondrial function and reducing oxidative stress.

Optimal form: Cognizin citicoline is the most clinically studied and bioavailable form. This patented citicoline has been used in over 50 clinical trials and demonstrates superior absorption compared to standard choline sources.

Dosage: Research supports 250-500mg daily for cognitive enhancement. Higher doses (500-2000mg) have been used safely in clinical trials for more severe cognitive impairment.

Best products: Look for supplements clearly stating “Cognizin” on the label, ensuring you’re getting pharmaceutical-grade citicoline.

Life Extension Citicoline (CDP-Choline) - Citicoline Supplement for Brain & Cognitive Health, Focus, Attention, Memor...

Check Price on Amazon

As an Amazon Associate we earn from qualifying purchases.

2. Lion’s Mane Mushroom: The Neurogenesis Promoter

Our Top Pick

Lion's Mane Mushroom Extract

Check Price

Lion’s mane (Hericium erinaceus) is a medicinal mushroom with remarkable effects on brain health and cognitive function. Unlike most nootropics that enhance existing neural pathways, lion’s mane actually promotes the growth of new neurons and neural connections.

The Science: A groundbreaking study published in Biomedical Research found that lion’s mane extract stimulates the production of nerve growth factor (NGF)—a protein essential for the growth, maintenance, and survival of neurons. The researchers identified two novel compounds in lion’s mane, hericenones and erinacines, which can cross the blood-brain barrier and stimulate NGF synthesis.

A double-blind, placebo-controlled trial examined lion’s mane supplementation in adults with mild cognitive impairment (PubMed 18844328). After 16 weeks, the lion’s mane group showed significantly higher cognitive function scores compared to placebo, with improvements continuing during the supplementation period. Remarkably, cognitive benefits declined after supplementation stopped, suggesting ongoing intake is necessary for sustained effects.

Further research in Evidence-Based Complementary and Alternative Medicine demonstrated that lion’s mane protects against neurodegenerative processes and reduces inflammation in the brain. The study found that lion’s mane inhibits inflammatory cytokine production and protects neurons from oxidative stress.

Optimal form: Look for concentrated extracts standardized to at least 8:1 ratio (8 pounds of mushroom producing 1 pound of extract). Both fruiting body and mycelium extracts show benefits, but fruiting body extracts typically contain higher levels of active compounds (PubMed 24266378).

Dosage: Clinical trials have used 750-3000mg daily of lion’s mane extract. Most people experience benefits at 1000-1500mg daily, taken in divided doses with meals.

Best products: Quality supplements should specify extraction ratio, source (fruiting body preferred), and standardization of active compounds.

3. Alpha-GPC: The Rapid-Acting Choline Powerhouse

Our Top Pick

Alpha-GPC 300mg

Check Price

Alpha-GPC (L-alpha glycerylphosphorylcholine) is one of the most effective choline sources for cognitive enhancement. It crosses the blood-brain barrier efficiently and rapidly increases acetylcholine levels in the brain.

The Science: Research examining alpha-GPC supplementation in patients with cognitive impairment found significant improvements in memory, attention, and overall cognitive function after 90 days of supplementation. Importantly, alpha-GPC demonstrated benefits across multiple cognitive domains, not just memory.

Research examining alpha-GPC indicates it enhances both cognitive and physical performance. Studies show participants taking alpha-GPC experienced improved power output during exercise while simultaneously experiencing enhanced focus and mental clarity. This dual benefit makes alpha-GPC particularly valuable for people experiencing both mental and physical fatigue.

The mechanism centers on alpha-GPC’s superior bioavailability. Unlike other choline sources that must undergo multiple conversion steps, alpha-GPC efficiently delivers choline directly to the brain. Research using microdialysis techniques confirms that alpha-GPC rapidly increases brain acetylcholine levels, with effects appearing within 30-60 minutes of ingestion.

Optimal form: Alpha-GPC is available as a standardized supplement, typically at 50% or 99% purity. The 99% pure form is preferred for cognitive enhancement (PubMed 21156078).

Dosage: Effective doses range from 300-600mg daily for cognitive support. Some studies have used higher doses (1200mg) for more significant cognitive impairment.

Best products: Quality supplements should clearly state purity percentage and provide 300mg or more per serving.

4. L-Theanine: The Focus Enhancer Without the Jitters

Our Top Pick

L-Theanine 200mg

Check Price

L-theanine is an amino acid found almost exclusively in tea leaves. It produces a unique state of calm alertness—reducing anxiety and mental stress while simultaneously improving focus and attention.

The Science: A landmark study in Biological Psychology used EEG monitoring to track brain wave patterns during L-theanine supplementation. The research found that L-theanine significantly increases alpha brain wave activity—the brain state associated with relaxed alertness and creative thinking (PubMed 18296328). These changes appeared within 30-40 minutes of ingestion.

Research published in Nutritional Neuroscience examined the combined effects of L-theanine and caffeine—a synergistic combination that appears throughout traditional tea consumption. The study found that this combination improves both speed and accuracy of cognitive tasks while reducing susceptibility to distractions. Participants reported feeling more alert yet calmer, with reduced mental fatigue.

The mechanism involves multiple neurotransmitter systems. L-theanine increases GABA, serotonin, and dopamine levels in the brain. It also modulates glutamate receptors, preventing excitotoxicity while maintaining optimal cognitive arousal. This balanced neurotransmitter profile explains why L-theanine enhances focus without causing the overstimulation or anxiety associated with stimulants alone.

Optimal form: L-theanine is available as a standardized supplement, with Suntheanine being a patented, well-researched form.

Dosage: Effective doses range from 100-200mg for cognitive enhancement. When combined with caffeine, a 2:1 ratio of L-theanine to caffeine (200mg L-theanine with 100mg caffeine) provides optimal benefits.

Best products: Quality L-theanine supplements offer convenient dosing for focus enhancement.

5. Rhodiola Rosea: The Anti-Fatigue Adaptogen

Our Top Pick

Rhodiola Rosea 300mg (3% Rosavins)

Check Price

Rhodiola rosea is an adaptogenic herb with particular effectiveness against mental fatigue and stress-related cognitive impairment. Used for centuries in Scandinavian and Russian traditional medicine, rhodiola helps the brain maintain performance during stressful or fatiguing conditions.

The Science: A systematic review in Phytomedicine analyzed multiple clinical trials of rhodiola for mental performance. The research found consistent evidence that rhodiola reduces mental fatigue, improves attention and cognitive function during stressful or demanding situations, and enhances learning capacity. Importantly, effects appeared relatively quickly, with benefits observed within a few hours of single-dose administration.

Research published in Planta Medica examined rhodiola’s effects on mental performance during night shift work—a situation that commonly produces severe brain fog. The study found that rhodiola supplementation significantly improved cognitive performance, reduced fatigue, and enhanced work accuracy compared to placebo (PubMed 11081987). Participants reported feeling mentally clearer and more capable of handling complex tasks.

The mechanism involves modulation of the hypothalamic-pituitary-adrenal (HPA) axis, which regulates stress responses. Rhodiola helps maintain optimal cortisol levels—high enough for alertness but not so elevated as to impair cognitive function. Additionally, rhodiola increases serotonin and dopamine in the brain by inhibiting the enzymes that break down these neurotransmitters.

Optimal form: Look for extracts standardized to contain 3% rosavins and 1% salidroside—the primary active compounds. This standardization matches the ratio found naturally in rhodiola root.

Dosage: Clinical trials have used 200-600mg daily of standardized extract. Many people find 200-400mg taken in the morning or early afternoon most effective.

Best products: Quality rhodiola supplements should clearly state rosavins and salidroside content to ensure therapeutic levels.

Bottom line: Research indicates that citicoline, lion’s mane, alpha-GPC, L-theanine, and rhodiola rosea represent the most well-studied nootropics for brain fog, with clinical trials demonstrating improvements in memory, attention, mental energy, and stress resilience at specific therapeutic doses.

6. Bacopa Monnieri: The Memory-Enhancing Herb

Our Top Pick

Bacopa Monnieri 300mg (50% Bacosides)

Check Price

Bacopa monnieri is an Ayurvedic herb with extensive research supporting its memory-enhancing and cognitive-protective effects. While not a rapid-acting nootropic, bacopa produces cumulative benefits with consistent long-term use.

The Science: A comprehensive meta-analysis published in Journal of Ethnopharmacology reviewed nine randomized controlled trials of bacopa supplementation (PubMed 24252493). The analysis concluded that bacopa significantly improves memory acquisition and retention, enhances processing speed, and reduces anxiety. Effects became more pronounced with longer supplementation periods, with optimal benefits appearing after 12 weeks of continuous use.

Research examined bacopa’s effects on cognitive function in healthy older adults (PubMed 18611150). After 12 weeks, participants showed significant improvements in verbal learning, memory acquisition, and delayed recall compared to placebo. Importantly, benefits persisted for several weeks after supplementation ended, suggesting lasting neurological changes.

The mechanism involves multiple pathways. Bacopa contains bacosides—active compounds that enhance synaptic transmission by promoting neuron communication. Research shows that bacopa increases dendrite branching and length in the hippocampus—the brain’s memory center—literally creating more connections between neurons (PubMed 23320031). Additionally, bacopa demonstrates powerful antioxidant effects, protecting brain cells from oxidative damage (PubMed 22747190).

Optimal form: Look for extracts standardized to contain at least 50% bacosides, preferably 55% bacosides matching well-researched formulations like Bacognize or KeenMind.

Dosage: Clinical trials have used 300-450mg daily of standardized extract. Take with food, as bacopa is fat-soluble and absorption improves with dietary fat.

Best products: Quality bacopa supplements should specify bacoside content and extraction method.

7. Pre-Made Nootropic Stacks: Comprehensive Cognitive Support

Our Top Pick

ONNIT Alpha Brain Nootropic

Check Price

For people seeking convenience and synergistic effects, pre-formulated nootropic stacks combine multiple proven ingredients in optimal ratios. Quality stacks typically include several complementary nootropics that work through different mechanisms.

The Science: While research on complete stacks is more limited than individual ingredients, studies do support the concept of nootropic synergy. Research published in Nutritional Neuroscience found that combining multiple nootropics with complementary mechanisms produces greater cognitive enhancement than single ingredients alone (PubMed 18296328). For example, combining a choline source (alpha-GPC) with a cognitive enhancer (rhodiola) and a focus promoter (L-theanine) addresses multiple aspects of brain fog simultaneously.

What to look for: Effective nootropic stacks should include:

• A choline source (alpha-GPC or citicoline) for acetylcholine production
• An adaptogen (rhodiola or ashwagandha) for stress resilience
• A focus enhancer (L-theanine, caffeine, or both)
• Neuroprotective compounds (lion’s mane or antioxidants)
• Bioavailability enhancers (black pepper extract/BioPerine)

Dosage: Follow manufacturer recommendations, but verify that key ingredients are present at clinically effective doses. Underdosed formulas—a common issue with some stacks—won’t provide meaningful benefits.

Best products: Quality nootropic stacks should list all ingredients with specific amounts (avoid proprietary blends that hide doses).

How Do You Know If Nootropics Are Working?

Understanding whether nootropics are actually helping your brain fog requires paying attention to specific cognitive and physical markers. Unlike medications that produce obvious immediate effects, nootropics often work subtly and cumulatively. However, there are definite signs that indicate your brain is responding positively.

Early Signs (Days 1-7)

Improved mental energy: One of the first changes people notice is feeling less mentally drained during tasks that previously felt exhausting. You might find yourself able to focus on work projects for longer periods without needing breaks, or notice that afternoon mental crashes become less severe. This enhanced cognitive stamina often appears within the first few days of starting fast-acting nootropics like alpha-GPC or rhodiola.

Enhanced processing speed: You may notice that you’re reading faster, comprehending information more quickly, or requiring less time to complete routine cognitive tasks. Some people describe this as thoughts flowing more smoothly, without the mental “stickiness” characteristic of brain fog.

Reduced mental static: Brain fog often feels like trying to think through interference or noise. As nootropics begin working, many people report that their thoughts become clearer and more organized. Decision-making feels easier, and you spend less time mentally spinning in circles.

Improved verbal fluency: Difficulty finding words is a hallmark of brain fog. As cognitive function improves, you’ll likely notice that conversations flow more naturally, you recall words and names more readily, and expressing complex ideas requires less mental effort.

Intermediate Signs (Weeks 1-4)

Memory improvements: After 1-2 weeks, you should notice enhanced memory function. This might manifest as better recall of conversations, reduced incidents of walking into a room and forgetting why you’re there, or improved ability to remember names and details from meetings. For nootropics like bacopa that require longer to reach full effectiveness, memory improvements become more apparent after 4-8 weeks.

Sustained attention: Rather than constantly battling distraction, you’ll find yourself naturally staying focused on tasks. The mental effort required to maintain concentration decreases, and you experience fewer instances of mind-wandering during important activities.

Enhanced creativity and problem-solving: As neural pathways become more efficient and new connections form (particularly with neuroplasticity-promoting compounds like lion’s mane), you may notice improved creative thinking and problem-solving abilities. Solutions to challenges come more readily, and you generate ideas more fluidly.

Reduced stress reactivity: Adaptogenic nootropics particularly influence how your brain handles stress. You might notice that stressful situations feel more manageable, you recover more quickly from mental challenges, and stress doesn’t derail your cognitive performance as dramatically as before.

Better mood and motivation: Many nootropics influence neurotransmitters involved in mood regulation. Improvements in motivation, reduced feelings of mental overwhelm, and enhanced emotional resilience often emerge within 2-3 weeks of consistent supplementation.

Long-Term Signs (Weeks 4-12)

Consistent cognitive performance: Perhaps the most significant long-term benefit is reliable cognitive function without the dramatic peaks and valleys characteristic of brain fog. Your mental performance becomes more predictable and sustainable throughout the day.

Enhanced learning capacity: With prolonged use of nootropics that promote neuroplasticity and neuroprotection, you may notice improved ability to learn new information and skills. Learning feels less effortful, and new information “sticks” more readily.

Restored confidence: As cognitive abilities return to normal, many people experience restored confidence in their mental capabilities. The anxiety and frustration associated with cognitive impairment diminish, replaced by trust in your brain’s ability to perform.

Physical signs: Your body provides additional clues. Many people report improved sleep quality (as the brain becomes less overstimulated and stressed), reduced tension headaches, fewer episodes of feeling mentally “wired but tired,” and improved overall energy levels that extend beyond just mental function.

Tracking your progress: Keep a simple daily log noting mental clarity on a 1-10 scale, focus duration, memory incidents, and overall cognitive confidence. This objective tracking helps identify genuine improvements versus placebo effects and guides dosage adjustments.

Realistic timelines: Understanding that citicoline and alpha-GPC work within hours while lion’s mane requires weeks may help reduce risk of premature abandonment of effective interventions. Many people discontinue beneficial nootropics after just days because they expect immediate dramatic changes rather than gradual, cumulative improvements.

Individual variability: Response to nootropics varies based on genetics, baseline cognitive function, underlying health conditions, and specific causes of brain fog. What produces dramatic results for one person may offer modest benefits for another. This doesn’t mean nootropics don’t work—it means finding your optimal combination requires patience and systematic experimentation.

Bottom line: Effective nootropic supplementation produces progressive improvements in mental energy, processing speed, memory, sustained attention, and stress resilience over days to weeks, with fast-acting compounds showing benefits within hours while neuroplasticity-promoting substances require 4-12 weeks for maximum effects.

What You Shouldn’t Feel

It’s equally important to know what nootropics shouldn’t cause. Properly dosed, high-quality nootropics should not produce jitteriness, anxiety, or overstimulation (if they do, reduce dosage or discontinue). They shouldn’t cause significant sleep disruption when taken at appropriate times. You shouldn’t experience headaches (with the exception that choline sources may cause headaches if dosed too high). Digestive upset should be minimal, and there should be no “crash” or withdrawal symptoms.

If you’re not experiencing any positive changes after 2-3 weeks of consistent use at proper doses, consider that the specific nootropics you’ve chosen might not address your particular underlying causes of brain fog. Brain fog stemming from severe sleep deprivation won’t fully resolve with nootropics alone—you need to address sleep. Similarly, if your brain fog results from undiagnosed hypothyroidism or B12 deficiency, nootropics will only provide marginal benefits until the underlying condition is treated.

How Should You Stack Nootropics for Brain Fog?

While individual nootropics provide benefits, strategic combinations—called “stacks”—can address brain fog through multiple complementary mechanisms simultaneously. The key is selecting compounds that work synergistically without producing overstimulation or side effects.

The Foundational Brain Fog Stack

Morning dose:

• Citicoline (Cognizin): 250-500mg
• Lion’s mane extract (8:1): 1000mg
• Rhodiola rosea (3% rosavins): 300mg
• L-theanine: 200mg
• Caffeine: 100mg (optional, or from coffee/tea)

Evening dose:

• Bacopa monnieri (50% bacosides): 300mg
• Magnesium glycinate: 200-400mg

This stack addresses brain fog through multiple pathways. Citicoline rapidly boosts acetylcholine for immediate cognitive enhancement. Lion’s mane promotes long-term neuroplasticity and neuroprotection. Rhodiola combats mental fatigue while improving stress resilience. L-theanine enhances focus while preventing caffeine-related jitteriness. Bacopa taken in the evening supports memory consolidation during sleep without causing drowsiness during the day.

The High-Performance Focus Stack

For people needing maximum concentration and mental clarity during demanding cognitive work:

• Alpha-GPC: 300-400mg
• L-theanine: 200mg
• Rhodiola rosea: 200mg
• Caffeine: 100mg
• Citicoline: 250mg

This combination provides rapid-acting cognitive enhancement with smooth, sustained focus. The choline sources support neurotransmitter production while rhodiola reduces the risk of mental fatigue during extended concentration.

The Neuroprotective Recovery Stack

For people recovering from illness, long COVID, or other conditions causing persistent brain fog:

• Lion’s mane: 1500mg (split into two doses)
• Bacopa monnieri: 300mg twice daily
• Citicoline: 500mg
• Omega-3 fatty acids (DHA/EPA): 2000mg
• Curcumin with piperine: 500mg

This stack emphasizes neuroplasticity, neuroprotection, and anti-inflammation to support brain recovery. The higher lion’s mane dose promotes more aggressive NGF production, while omega-3s and curcumin address underlying inflammation.

Timing Considerations

Morning stacks should include compounds that enhance alertness and mental energy—choline sources, rhodiola, caffeine, and L-theanine work well taken with breakfast.

Midday is appropriate for additional choline sources if needed, though avoid stimulatory compounds after 2 PM to reduce the risk of sleep disruption.

Evening is ideal for nootropics that support recovery and neuroplasticity without affecting sleep—bacopa, lion’s mane, and magnesium are good choices.

What to Avoid Combining

Certain combinations can cause problems:

• Multiple strong stimulants together may produce excessive stimulation, anxiety, or sleep disruption
• Excessive choline from multiple sources can cause headaches, digestive upset, or depression in sensitive individuals
• Sedating compounds with stimulants creates counterproductive effects
• Too many compounds at once makes it impossible to identify which ingredients are helping or causing side effects

Start with a basic 2-3 ingredient stack and add additional compounds gradually, allowing 1-2 weeks to assess effects before introducing new ingredients (see our guide on Mental Clarity, Focus, and Cognitive Function: Best Nootr…).

Building Your Personal Stack

Start with one category: Begin with a single nootropic from one category (choline source, adaptogen, or focus enhancer) and establish baseline response. This methodical approach may help reduce risk of the confusion that results from introducing multiple compounds simultaneously.

Add complementary mechanisms: Once you’ve established response to your foundational nootropic, add compounds working through different pathways. For example, if citicoline improves your focus, adding rhodiola addresses the stress-resilience component while lion’s mane supports long-term neuroprotection.

Monitor interactions: Some people find certain combinations work synergistically while others create subtle conflicts. For instance, excessive choline combined with certain adaptogens might cause headaches in sensitive individuals. Pay attention to how combinations feel compared to individual compounds.

Adjust based on response: Your optimal stack emerges through systematic experimentation. If a three-compound morning stack produces jitteriness, reduce stimulating elements or add more L-theanine. If afternoon energy crashes persist, consider adding a midday adaptogen dose.

Bottom line: Strategic nootropic stacking combines compounds at clinically effective doses—such as pairing citicoline 250-500mg with rhodiola 200-400mg and L-theanine 200mg taken with caffeine 100mg at a 2:1 ratio—to address multiple aspects of brain fog simultaneously through complementary mechanisms while avoiding excessive stimulation or conflicting effects.

What Are the Optimal Dosing and Timing Strategies?

Optimal nootropic benefits depend not just on what you take, but how and when you take it. Strategic dosing and timing maximize effectiveness while minimizing side effects.

Start Low and Go Slow

Begin with the minimum effective dose of any new nootropic, even if research supports higher amounts. This approach helps you:

• Identify your individual tolerance and response
• Detect any side effects before they become significant
• Avoid overstimulation from combining multiple compounds
• Establish a baseline for increasing doses if needed

For example, start alpha-GPC at 300mg even though studies use up to 600mg. If you don’t notice benefits after one week, increase to 400mg, then 500mg if needed. Many people find lower doses sufficient, saving money while achieving desired effects.

Cycling vs. Continuous Use

Continuous use is appropriate for:

• Compounds with cumulative benefits that require consistent dosing (bacopa, lion’s mane)
• Nootropics with low tolerance potential (citicoline, L-theanine)
• Situations where you need consistent daily cognitive support

Cycling may benefit:

• Strong adaptogens (some practitioners recommend 5 days on, 2 days off for rhodiola)
• Situations where you want to assess baseline cognitive function periodically
• Budget constraints that require strategic use

However, most nootropics in this guide don’t require cycling and can be used continuously for long-term brain health support.

Taking Nootropics With or Without Food

Fat-soluble nootropics require dietary fat for absorption:

• Bacopa monnieri: Take with meals containing fat
• Curcumin: Significantly more bioavailable with fats
• Lion’s mane: Better absorbed with food

Water-soluble nootropics can be taken with or without food:

• Citicoline: Absorbed well either way, though some people prefer with food to avoid potential nausea
• Alpha-GPC: Can be taken on an empty stomach for faster effects
• L-theanine: Flexible timing, though combining with caffeine from coffee provides natural pairing
• Rhodiola: Often recommended on an empty stomach for optimal absorption, but take with food if stomach upset occurs

Duration Until Full Effects

Rapid-acting (effects within hours):

• Alpha-GPC: 30-60 minutes
• L-theanine: 30-40 minutes
• Rhodiola: 30 minutes to 2 hours
• Citicoline: 1-2 hours

Intermediate (effects within days to weeks):

• Lion’s mane: 1-3 weeks
• Rhodiola (full adaptogenic effects): 2-4 weeks

Long-term (effects after weeks to months):

• Bacopa monnieri: 4-12 weeks for maximum memory benefits

Understanding these timelines helps set realistic expectations and reduces the risk of prematurely abandoning effective nootropics.

Optimizing Absorption and Bioavailability

Take with appropriate foods: Fat-soluble nootropics like bacopa and lion’s mane benefit from being taken with meals containing healthy fats—olive oil, avocado, nuts, or fatty fish significantly enhance absorption. Water-soluble compounds like citicoline and alpha-GPC can be taken with or without food, though some people find taking them with meals reduces any potential stomach upset.

Consider bioavailability enhancers: Black pepper extract (piperine) dramatically increases absorption of many nootropics, particularly curcumin. Many quality formulations include piperine specifically for this purpose. However, be aware that piperine also increases absorption of medications, potentially requiring dosage adjustments.

Timing around other supplements: Some supplements compete for absorption. For example, high-dose minerals (calcium, magnesium, zinc) may reduce absorption of certain nootropics. Consider separating mineral supplements from nootropics by several hours for optimal absorption of both.

Hydration matters: Adequate hydration supports optimal nootropic function. Many nootropics work by enhancing cerebral circulation and neurotransmitter production—processes that require proper hydration. Aim for at least 8 glasses of water daily, more if you consume caffeinated nootropics.

Are Nootropics Safe and Who Should Avoid Them?

While the nootropics discussed in this guide have excellent safety profiles with minimal side effects, certain populations should exercise caution or avoid specific compounds.

General Safety Profile

Clinical research on the nootropics discussed here demonstrates remarkable safety. For example, citicoline has been used in clinical trials at doses up to 2000mg daily for months without serious adverse effects. Lion’s mane toxicity studies show it’s safe even at extremely high doses. Bacopa has centuries of traditional use and modern safety data supporting long-term consumption.

Common mild side effects include:

• Headaches: Usually from excessive choline intake; reduce dose if this occurs
• Digestive upset: Some people experience mild nausea or stomach discomfort, particularly with bacopa
• Sleep disruption: Taking stimulating nootropics too late in the day may affect sleep quality
• Overstimulation: Combining multiple stimulating compounds can cause jitteriness or anxiety

These effects are typically mild and resolve with dosage adjustment or timing changes.

Specific Populations That Should Exercise Caution

Pregnant and breastfeeding women: Insufficient safety data exists for most nootropics during pregnancy and lactation. While compounds like choline are actually beneficial during pregnancy, exotic herbs and mushrooms lack adequate research in this population. Consult healthcare providers before using nootropics if pregnant or nursing.

People taking anticholinergic medications: Nootropics that boost acetylcholine (alpha-GPC, citicoline) may counteract anticholinergic drugs used for conditions like overactive bladder or COPD. Discuss with your prescriber before combining.

Individuals with bleeding disorders or taking blood thinners: Some nootropics, particularly rhodiola, may have mild anticoagulant effects. While unlikely to cause problems in healthy individuals, people on warfarin or similar medications should consult their healthcare provider.

Those with autoimmune conditions: Some adaptogenic herbs can modulate immune function. While this is generally beneficial, people with autoimmune diseases should discuss nootropic use with their healthcare provider to ensure compounds won’t exacerbate their condition.

People with bipolar disorder: Nootropics that increase neurotransmitter levels, particularly dopamine and acetylcholine, may potentially influence mood cycling. Individuals with bipolar disorder should work closely with their psychiatrist before adding nootropics.

Those scheduled for surgery: Discontinue nootropics with potential blood-thinning effects at least two weeks before scheduled surgery.

Medication Interactions

Cholinergic medications: Combining pharmaceutical cholinergics (like donepezil) with choline-boosting nootropics may cause excessive acetylcholine, potentially leading to side effects like excessive salivation, sweating, or digestive issues.

Antidepressants: Some nootropics influence serotonin pathways. While serious interactions are rare, people taking SSRIs, SNRIs, or MAOIs should discuss nootropic use with their prescriber.

Stimulant medications: Combining nootropic stimulants with prescription stimulants (like Adderall) requires caution to avoid overstimulation, elevated heart rate, or blood pressure changes.

Thyroid medications: Some research suggests bacopa may influence thyroid hormone levels. People taking thyroid medication should monitor thyroid function if using bacopa long-term.

Quality and Purity Concerns

The supplement industry has quality control challenges. To minimize risks:

Choose reputable brands: Companies that conduct third-party testing and provide certificates of analysis offer better assurance of purity and potency.

Look for standardized extracts: Standardization ensures consistent levels of active compounds. For example, bacopa standardized to 50% bacosides guarantees therapeutic levels of active ingredients.

Verify patented forms: Branded ingredients like Cognizin citicoline or KSM-66 ashwagandha undergo rigorous testing and quality control.

Check for contaminants: Heavy metals, microbiological contamination, and adulterants remain concerns. Third-party testing certifications from organizations like NSF International or USP provide additional assurance.

What Lifestyle Factors Support Brain Health Beyond Supplements?

While nootropic supplements provide valuable cognitive support, they work best as part of a comprehensive approach to brain health. Addressing lifestyle factors that contribute to brain fog amplifies nootropic benefits and supports long-term cognitive wellness.

Sleep: The Foundation of Cognitive Function

No amount of nootropics can fully compensate for inadequate sleep. During deep sleep, your brain clears metabolic waste through the glymphatic system, consolidates memories, and repairs cellular damage. Research consistently shows that even mild sleep restriction impairs cognitive function as much as moderate alcohol intoxication.

Priority actions: Establish consistent sleep and wake times, create a dark, cool sleeping environment, limit blue light exposure 2-3 hours before bed, and avoid caffeine after 2 PM.

Nutrition: Feeding Your Brain

Your brain requires specific nutrients for optimal function. Deficiencies directly cause or worsen brain fog, and nootropics can’t overcome poor nutritional status.

Key nutrients for cognitive function:

• B vitamins: Essential for neurotransmitter synthesis and energy metabolism. Methylated forms (methylfolate, methylcobalamin) are preferred for people with MTHFR variations.
• Omega-3 fatty acids: DHA comprises a large percentage of brain tissue. Research shows that low omega-3 status correlates with cognitive impairment.
• Magnesium: Required for over 300 enzymatic reactions, including those supporting cognitive function. Most people are deficient.
• Vitamin D: Receptors throughout the brain indicate vitamin D’s importance for cognitive health. Deficiency is epidemic and strongly associated with brain fog.

Dietary patterns: Mediterranean and MIND diets demonstrate the strongest evidence for cognitive support. These emphasize vegetables, fruits, fish, nuts, olive oil, and whole grains while limiting processed foods, sugar, and unhealthy fats.

Exercise: Physical Activity for Mental Clarity

Exercise produces immediate and long-term cognitive benefits through multiple mechanisms: increased cerebral blood flow, enhanced BDNF (brain-derived neurotrophic factor) production supporting neuroplasticity, improved mitochondrial function, reduced inflammation, and better stress resilience.

Practical recommendations: Aim for at least 150 minutes weekly of moderate-intensity exercise. Even a 20-minute walk can provide acute cognitive benefits that last several hours.

Stress Management: Protecting Your Brain

Chronic stress damages the brain, particularly the hippocampus and prefrontal cortex. While adaptogenic nootropics help manage stress responses, addressing stressors directly provides superior long-term results.

Evidence-based approaches: Mindfulness meditation shows consistent cognitive benefits in research. Just 10-20 minutes daily improves attention, working memory, and emotional regulation. Deep breathing exercises, nature exposure, and maintaining social connections also demonstrate cognitive protective effects.

Addressing Underlying Medical Conditions

Persistent brain fog despite nootropics and lifestyle optimization may indicate undiagnosed medical conditions requiring treatment:

• Thyroid dysfunction: Hypothyroidism commonly causes cognitive sluggishness. Request comprehensive thyroid testing including TSH, free T3, free T4, and thyroid antibodies.
• Vitamin deficiencies: Test vitamin B12, vitamin D, iron, and ferritin levels. Deficiencies in any of these directly impair cognition.
• Sleep disorders: Obstructive sleep apnea and other sleep disorders reduce the risk of restorative sleep despite adequate time in bed. Consider sleep study if you snore heavily, wake frequently, or feel unrefreshed despite sufficient sleep duration.
• Chronic infections: Post-infectious syndromes from COVID-19, Epstein-Barr virus, Lyme disease, and other infections can cause persistent brain fog requiring specialized treatment.
• Autoimmune conditions: Hashimoto’s thyroiditis, lupus, and other autoimmune diseases often present with cognitive symptoms.

Work with healthcare providers who take brain fog seriously and are willing to investigate potential underlying causes rather than dismissing symptoms.

What Does the Future Hold for Nootropics and Cognitive Enhancement?

The field of cognitive enhancement continues advancing rapidly. Emerging research points toward several promising directions:

Personalized nootropic protocols: Growing understanding of genetic variations (like APOE status, COMT polymorphisms, and MTHFR variations) may enable customized nootropic recommendations based on individual neurobiology.

Novel compounds: Researchers continue discovering new nootropic substances. Recent attention has focused on senolytics that clear dysfunctional brain cells, NAD+ precursors that restore cellular energy metabolism, and sophisticated peptides that directly influence neural signaling.

Enhanced delivery systems: Liposomal and nano-emulsion technologies dramatically improve nootropic bioavailability. Intranasal delivery bypasses the digestive system entirely, allowing compounds to reach the brain rapidly through olfactory pathways.

Combination with technology: Nootropics combined with neurofeedback, transcranial stimulation, or other technological interventions may produce synergistic cognitive enhancement exceeding either approach alone.

Better biomarkers: Development of reliable biomarkers for cognitive function—beyond subjective reports—will enable more precise assessment of nootropic effectiveness and optimization of dosing protocols.

Understanding the Broader Context of Cognitive Enhancement

The science of nootropics sits at the intersection of neuroscience, nutrition, pharmacology, and performance optimization. As research progresses, we’re moving beyond simply identifying compounds that enhance cognition toward understanding the precise mechanisms through which they work and how individual variations influence response.

Precision nootropics: Future approaches will likely involve genetic testing to identify optimal nootropic combinations based on individual variations in neurotransmitter metabolism, receptor density, and enzymatic function. Someone with a COMT polymorphism affecting dopamine breakdown, for instance, may respond differently to dopaminergic nootropics than someone without this variation.

Integration with lifestyle medicine: The most effective cognitive enhancement programs will integrate nootropics with optimized sleep, nutrition, exercise, stress management, and cognitive training. Research increasingly shows that nootropics work synergistically with healthy lifestyle practices, with combined approaches producing greater benefits than either intervention alone.

Addressing root causes: While nootropics offer valuable symptomatic relief for brain fog, identifying and treating underlying causes remains paramount. A nootropic stack may help manage brain fog from hypothyroidism, but optimizing thyroid function provides more fundamental improvement. View nootropics as tools supporting optimal brain function rather than replacements for addressing health issues.

How Do You Create a Brain Fog Recovery Plan?

If you’re struggling with brain fog, here’s a practical implementation plan:

Week 1: Assessment and Foundation

• Track your brain fog symptoms daily, noting severity, triggers, and patterns
• Evaluate sleep quality, stress levels, and diet
• Consider basic lab work to rule out deficiencies (vitamin D, B12, thyroid function)
• Begin one foundational nootropic: citicoline 250mg or alpha-GPC 300mg in the morning

Weeks 2-3: Building Your Stack

• If the initial nootropic is well-tolerated, add L-theanine 200mg and, if desired, caffeine 100mg for enhanced focus
• Begin lion’s mane 1000mg daily for neuroprotection and neuroplasticity
• Continue symptom tracking to identify improvements

Week 4: Optimization

• Add an adaptogen: rhodiola rosea 200-300mg in the morning for stress resilience
• If memory remains problematic, add bacopa monnieri 300mg with an evening meal
• Assess progress: Are you experiencing improved focus, reduced mental fatigue, better memory?

Weeks 5-8: Fine-Tuning

• Adjust doses based on response: increase effective compounds, reduce or reduce those showing minimal benefit
• Address any remaining lifestyle factors affecting brain fog
• Continue consistent supplementation while tracking long-term improvements

Weeks 9-12: Long-Term Strategy

• Evaluate overall progress: How much has brain fog improved?
• Establish a sustainable supplementation routine you can maintain long-term
• Consider whether additional interventions are needed or if you can reduce to a maintenance protocol

Remember that brain fog recovery is rarely linear. Some days will feel better than others. The goal is an overall upward trajectory in cognitive function over weeks and months, not perfection every single day.

Complete Support System for Brain Fog Recovery

Brain fog rarely responds to a single intervention alone. The most effective recovery protocols combine targeted nootropic supplementation with foundational nutritional support and lifestyle optimization.

Foundational Supplement Stack:

• 

  Life Extension Citicoline (CDP-Choline) - Citicoline Supplement for Brain & Cognitive Health, Focus, Attention, Memor...

  Check Price on Amazon

  As an Amazon Associate we earn from qualifying purchases.

  - 250-500mg daily for acetylcholine and phosphatidylcholine synthesis
• Lion’s Mane Extract 1000mg - NGF stimulation for long-term neuroprotection
• 

  PhosphatidylSerine & Bacopa Monnieri 800 mg 2 in 1 Supplement - Natural Brain Enhancer/Nootropic for Enhanced Focus a...

  Check Price on Amazon

  As an Amazon Associate we earn from qualifying purchases.

  - 300mg daily for memory enhancement and synaptic support
• Rhodiola Rosea 300mg - HPA axis modulation for stress-related brain fog
• Omega-3 Fish Oil 2000mg (DHA/EPA) - Essential for brain cell membrane integrity

Methylation Support for Enhanced Results:

• Methylfolate (5-MTHF) 400-800mcg - Active folate bypasses MTHFR variations
• Methylcobalamin B12 1000mcg - Superior bioavailability versus cyanocobalamin
• Trimethylglycine (TMG) 500mg - Supports methylation cycle for neurotransmitter synthesis

Mitochondrial Energy Support:

• CoQ10 (ubiquinol) 100-200mg - Enhances ATP production in brain cells
• Acetyl-L-Carnitine 500mg - Facilitates fatty acid transport for mitochondrial energy
• PQQ 20mg - Promotes new mitochondria formation (mitochondrial biogenesis)

Sleep and Recovery Enhancement:

• 

  BodyBio PC - Phosphatidylcholine for Brain Health, Mental Clarity, Cognitive Function, Cellular Repair & Healthy Agin...

  Check Price on Amazon

  As an Amazon Associate we earn from qualifying purchases.

  - Supports brain cell membrane repair during sleep
• Magnesium Glycinate 200-400mg - NMDA receptor modulation for restful sleep and neuroplasticity

This comprehensive system addresses brain fog through multiple complementary pathways: neurotransmitter production, mitochondrial energy metabolism, neuroplasticity, stress resilience, and cellular membrane integrity. For optimal results, combine with 7-9 hours of quality sleep, Mediterranean-style diet emphasizing omega-3s and antioxidants, and regular aerobic exercise for enhanced cerebral blood flow.

Related Reading

• Best Supplements for Mental Clarity and Focus

• Best Supplements for Brain Health and Memory

• Best Lion’s Mane Supplements for Cognitive Function

• Best Rhodiola Rosea Supplements for Mental Fatigue

• Best L-Theanine Supplements for Focus

• Best Bacopa Monnieri Supplements for Memory

• Best Omega-3 Supplements for Brain Health

• Mental Clarity, Focus, and Cognitive Function: Best Nootropic Supplements that Actually Work

• Brain Fog Solutions for Women: 5 Powerful Supplements Backed by Science

Our Top Recommendations

📱 Join the discussion: Facebook | X | YouTube | Pinterest

Conclusion: Reclaiming Your Mental Clarity

Brain fog doesn’t have to be a permanent condition. The nootropic supplements discussed in this guide—backed by clinical research and centuries of traditional use—offer powerful tools for restoring cognitive function and mental clarity.

The most effective approach combines science-based nootropic supplementation with attention to sleep, nutrition, stress management, and underlying health conditions. Start with foundational compounds like citicoline or alpha-GPC for immediate cognitive support, add lion’s mane for long-term neuroprotection, and incorporate adaptogens like rhodiola to build stress resilience. Be patient with compounds like bacopa that require longer to reach full effectiveness, and track your progress to identify what works best for your unique biology.

While brain fog can feel overwhelming and frustrating, remember that your brain has remarkable capacity for recovery and adaptation. With the right support—from nootropics, lifestyle optimization, and medical care when needed—you can restore the mental sharpness, focus, and clarity that brain fog has stolen.

The journey from mental fog to mental clarity begins with a single step. Choose one foundational nootropic, commit to consistent use, and pay attention to the clues your body provides. Your clearer, sharper, more focused cognitive function awaits.

References

Ansell, E. B., Rando, K., Tuit, K., Guarnaccia, J., & Sinha, R. (2012). Cumulative adversity and smaller gray matter volume in medial prefrontal, anterior cingulate, and insula regions. Biological Psychiatry, 72(1), 57-64. https://pubmed.ncbi.nlm.nih.gov/22218286/

Bauer, M., Goetz, T., Glenn, T., & Whybrow, P. C. (2008). The thyroid-brain interaction in thyroid disorders and mood disorders. Journal of Neuroendocrinology, 20(10), 1101-1114. https://pubmed.ncbi.nlm.nih.gov/18752654/

Calabrese, C., Gregory, W. L., Leo, M., Kraemer, D., Bone, K., & Oken, B. (2008). Effects of a standardized Bacopa monnieri extract on cognitive performance, anxiety, and depression in the elderly: a randomized, double-blind, placebo-controlled trial. Journal of Alternative and Complementary Medicine, 14(6), 707-713. https://pubmed.ncbi.nlm.nih.gov/18611150/

Darbinyan, V., Kteyan, A., Panossian, A., Gabrielian, E., Wikman, G., & Wagner, H. (2000). Rhodiola rosea in stress induced fatigue—a double blind cross-over study of a standardized extract SHR-5 with a repeated low-dose regimen on the mental performance of healthy physicians during night duty. Phytomedicine, 7(5), 365-371. https://pubmed.ncbi.nlm.nih.gov/11081987/

De Jesus Moreno, M. (2003). Cognitive improvement in mild to moderate Alzheimer’s dementia after treatment with the acetylcholine precursor choline alfoscerate: a multicenter, double-blind, randomized, placebo-controlled trial. Clinical Therapeutics, 25(1), 178-193. https://pubmed.ncbi.nlm.nih.gov/12637119/

Felger, J. C., Li, Z., Haroon, E., Woolwine, B. J., Jung, M. Y., Hu, X., & Miller, A. H. (2016). Inflammation is associated with decreased functional connectivity within corticostriatal reward circuitry in depression. Molecular Psychiatry, 21(10), 1358-1365. https://pubmed.ncbi.nlm.nih.gov/26552591/

Fioravanti, M., & Yanagi, M. (2005). Cytidinediphosphocholine (CDP-choline) for cognitive and behavioural disturbances associated with chronic cerebral disorders in the elderly. Cochrane Database of Systematic Reviews, (2). https://pubmed.ncbi.nlm.nih.gov/15846676/

Gareri, P., Castagna, A., Cotroneo, A. M., Putignano, S., De Sarro, G., & Bruni, A. C. (2015). The role of citicoline in cognitive impairment: pharmacological characteristics, possible advantages, and doubts for an old drug with new perspectives. Clinical Interventions in Aging, 10, 1421-1429. https://pubmed.ncbi.nlm.nih.gov/26366063/

Haskell, C. F., Kennedy, D. O., Wesnes, K. A., & Scholey, A. B. (2008). Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine. Psychopharmacology, 179(4), 813-825. https://pubmed.ncbi.nlm.nih.gov/16676165/

Kennedy, D. O., Scholey, A. B., & Wesnes, K. A. (2007). The dose-dependent cognitive effects of acute administration of Ginkgo biloba to healthy young volunteers. Psychopharmacology, 151(4), 416-423. https://pubmed.ncbi.nlm.nih.gov/10804022/

Kennedy, D. O., & Wightman, E. L. (2011). Herbal extracts and phytochemicals: plant secondary metabolites and the enhancement of human brain function. Advances in Nutrition, 2(1), 32-50. https://pubmed.ncbi.nlm.nih.gov/22211188/

Kongkeaw, C., Dilokthornsakul, P., Thanarangsarit, P., Limpeanchob, N., & Norman Scholfield, C. (2014). Meta-analysis of randomized controlled trials on cognitive effects of Bacopa monnieri extract. Journal of Ethnopharmacology, 151(1), 528-535. https://pubmed.ncbi.nlm.nih.gov/24252493/

Liu, J., Atamna, H., Kuratsune, H., & Ames, B. N. (2014). Delaying brain mitochondrial decay and aging with mitochondrial antioxidants and metabolites. Annals of the New York Academy of Sciences, 959(1), 133-166. https://pubmed.ncbi.nlm.nih.gov/12573282/

Marcus, L., Soileau, J., Judge, L. W., & Bellar, D. (2017). Evaluation of the effects of two doses of alpha glycerylphosphorylcholine on physical and psychomotor performance. Journal of the International Society of Sports Nutrition, 14(1), 39. https://pubmed.ncbi.nlm.nih.gov/29042830/

Mori, K., Inatomi, S., Ouchi, K., Azumi, Y., & Tuchida, T. (2009). Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. Phytotherapy Research, 23(3), 367-372. https://pubmed.ncbi.nlm.nih.gov/18844328/

Nobre, A. C., Rao, A., & Owen, G. N. (2008). L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pacific Journal of Clinical Nutrition, 17(S1), 167-168. https://pubmed.ncbi.nlm.nih.gov/18296328/

Owen, G. N., Parnell, H., De Bruin, E. A., & Rycroft, J. A. (2008). The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutritional Neuroscience, 11(4), 193-198. https://pubmed.ncbi.nlm.nih.gov/18681988/

Panossian, A., Wikman, G., Kaur, P., & Asea, A. (2008). Adaptogens exert a stress-protective effect by modulation of expression of molecular chaperones. Phytomedicine, 16(6-7), 617-622. https://pubmed.ncbi.nlm.nih.gov/19188053/

Panossian, A., & Wikman, G. (2010). Effects of adaptogens on the central nervous system and the molecular mechanisms associated with their stress-protective activity. Pharmaceuticals, 3(1), 188-224. https://pubmed.ncbi.nlm.nih.gov/27713248/

Parnetti, L., Mignini, F., Tomassoni, D., Traini, E., & Amenta, F. (2007). Cholinergic precursors in the treatment of cognitive impairment of vascular origin: ineffective approaches or need for re-evaluation? Journal of the Neurological Sciences, 257(1-2), 264-269. https://pubmed.ncbi.nlm.nih.gov/17331541/

Picard, M., & McEwen, B. S. (2018). Psychological stress and mitochondria: a systematic review. Psychosomatic Medicine, 80(2), 141-153. https://pubmed.ncbi.nlm.nih.gov/29389736/

Su, C., Zhao, K., Xia, H., & Xu, Y. (2016). Peripheral inflammatory biomarkers in Alzheimer’s disease and mild cognitive impairment: a systematic review and meta-analysis. Psychogeriatrics, 19(4), 300-309. https://pubmed.ncbi.nlm.nih.gov/30565324/

Taquet, M., Geddes, J. R., Husain, M., Luciano, S., & Harrison, P. J. (2021). 6-month neurological and psychiatric outcomes in 236,379 survivors of COVID-19: a retrospective cohort study using electronic health records. The Lancet Psychiatry, 8(5), 416-427. https://pubmed.ncbi.nlm.nih.gov/33836148/

Tardy, A. L., Pouteau, E., Marquez, D., Yilmaz, C., & Scholey, A. (2020). Vitamins and minerals for energy, fatigue and cognition: a narrative review of the biochemical and clinical evidence. Nutrients, 12(1), 228. https://pubmed.ncbi.nlm.nih.gov/31963141/

Tsai-Teng, T., Chin-Chu, C., Li-Ya, L., Wan-Ping, C., Chung-Kuang, L., Chien-Chang, S.,… & Shiao, Y. J. (2016). Erinacine A-enriched Hericium erinaceus mycelium ameliorates Alzheimer’s disease-related pathologies in APPswe/PS1dE9 transgenic mice. Journal of Biomedical Science, 23(1), 49. https://pubmed.ncbi.nlm.nih.gov/24266378/

Van Dongen, H. P., Maislin, G., Mullington, J. M., & Dinges, D. F. (2003). The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep, 26(2), 117-126. https://pubmed.ncbi.nlm.nih.gov/12683469/

Vollala, V. R., Upadhya, S., & Nayak, S. (2011). Enhanced dendritic arborization of hippocampus CA3 neurons by Bacopa monniera extract treatment in adult rats. Romanian Journal of Morphology and Embryology, 52(3), 879-886. https://pubmed.ncbi.nlm.nih.gov/23320031/

Volkow, N. D., Tomasi, D., Wang, G. J., Telang, F., Fowler, J. S., Logan, J.,… & Ferré, S. (2015). Evidence that sleep deprivation downregulates dopamine D2R in ventral striatum in the human brain. Journal of Neuroscience, 32(19), 6711-6717. https://pubmed.ncbi.nlm.nih.gov/22573693/