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Simon Parrott – Vitacuity Ltd
Chronic stress and anxiety can impair your memory, focus, and thinking ability. Ashwagandha, an ancient herb, may help by working on your body’s central stress-response system to lower cortisol (a stress hormone that damages brain tissue, especially the memory-forming region). Multiple studies show ashwagandha reduces anxiety and stress consistently, and recent research suggests these improvements are followed by better cognitive performance in stressed but otherwise healthy adults.
A small 2025 study of adults with mild cognitive impairment found meaningful improvements in memory and thinking after 60 days of ashwagandha, with scores improving significantly on multiple validated tests. However, most studies involve fewer than 100 participants and last only 8 to 12 weeks, so we need larger, longer trials to be confident about long-term benefits. The dose used in successful studies typically ranges from 250 to 500 milligrams daily.
The evidence suggests ashwagandha helps a stressed brain function closer to its actual capacity by reducing the cortisol load and improving sleep, though whether it also protects the brain directly in humans remains unclear. It appears well-tolerated with minimal side effects, though you should avoid it if you take thyroid medications or sedatives, and you should taper gradually if stopping.
Verdict: Ashwagandha is one of the better-supported supplements for stress and anxiety with emerging evidence of cognitive benefits, making it reasonable to consider if you’re experiencing stress-related memory or focus problems, but it works best alongside good sleep, movement, and stress management, not as a substitute for them.
What if the reason you can’t focus, remember names, or think clearly isn’t primarily a brain problem, but a stress problem? Most of us think of anxiety and cognitive decline as two separate health concerns. We worry about stress today and dementia sometime in the future, as if they exist in different compartments. But a growing body of research suggests they may be far more intertwined than that. Chronic stress and anxiety don’t just make you feel frazzled, they appear to actively impair the very cognitive systems you rely on for memory, attention, and mental agility. So the question becomes: if you address the anxiety, do you also protect the brain? And that’s exactly where ashwagandha, one of Ayurveda’s most ancient herbs, is starting to make a genuinely interesting case for itself. Vitacuity has reviewed over 1.77 million research papers to bring you the most relevant findings on this topic. Here’s what the science actually says.
Ashwagandha (*Withania somnifera*) is an adaptogen, a category of herbs that appear to help the body modulate its response to stress rather than simply switching it off. The plant’s active compounds, known as withanolides, appear to work through several distinct biological pathways simultaneously, which partly explains why researchers keep finding effects on such a broad range of outcomes.
The most well-understood mechanism involves the hypothalamic-pituitary-adrenal (HPA) axis, essentially your body’s central stress-response system. When you’re under sustained stress, this system pumps out cortisol, and chronically elevated cortisol is genuinely damaging to brain tissue, particularly in the hippocampus, the region most critical for memory formation [11]. Ashwagandha appears to modulate this axis, helping bring cortisol back towards normal levels [13].
But that’s not the whole story. Research suggests ashwagandha also interacts with GABAergic pathways, the brain’s primary “calm down” signalling system, the same one targeted by anti-anxiety medications like benzodiazepines, though through entirely different mechanisms [10]. It also shows antioxidant and anti-inflammatory properties, reduces something called apoptosis (the premature death of brain cells), and appears to promote synaptic plasticity, the brain’s ability to form and strengthen connections [10]. In animal models, it has been shown to modulate oxidative stress caused by sleep deprivation and combat neuroinflammation [3, 9]. The picture that emerges is of a herb that works upstream, addressing the stress and anxiety that impair cognition, while also appearing to offer some direct neuroprotective effects.
Evidence grade: Promising to Strong, Multiple RCTs with consistent direction, though sample sizes are modest and study durations rarely exceed 12 weeks.
The most rigorous synthesis of the evidence comes from a 2024 systematic review and meta-analysis that pooled data from nine randomised controlled trials involving 558 participants [15]. The results showed statistically significant reductions in perceived stress (Perceived Stress Scale mean difference: -4.72 points), Hamilton Anxiety Scale scores (mean difference: -2.19 points), and serum cortisol levels (mean difference: -2.58 nmol/L) compared to placebo.
These aren’t enormous effect sizes, but they are consistent, and consistency across multiple independent trials is exactly what you want to see. Earlier systematic review work from 2014 looked at five human trials and found all five concluded ashwagandha intervention resulted in greater improvements than placebo on anxiety or stress scales [12]. One standout finding from that review: Beck Anxiety Inventory scores dropped by 56.5% in an ashwagandha group compared to 30.5% in a psychotherapy group. That’s a striking number, though it’s worth noting the study design limitations mean we shouldn’t read too much into a head-to-head comparison.
A double-blind, placebo-controlled clinical study from 2019 tested two doses, 250 mg/day and 600 mg/day, across 60 healthy but stressed adults over eight weeks [13]. Both doses produced significant reductions in perceived stress and cortisol. The higher dose produced more significant cortisol reduction (p < 0.0001), suggesting there may be a meaningful dose-response relationship. Both groups also showed significant improvements in sleep quality compared to placebo.
Most recently, a 2025 RCT tested an ashwagandha formulation called Zenroot™ at just 125 mg/day in 90 subjects over 84 days [4]. Even at this lower dose, significant improvements in perceived stress, anxiety (Beck Anxiety Inventory), sleep quality, and mood were observed from day 28 onwards. Objective physiological measures, skin conductance response and heart rate variability, also showed measurable changes, lending credibility beyond self-report.
Evidence grade: Promising, Consistent direction across human trials, though samples are small and mechanisms require further clarification.
Here’s where the anxiety-cognition link becomes particularly interesting. A 2022 randomised trial tested two doses of ashwagandha (225 mg/day and 400 mg/day) versus placebo in 60 adults with self-reported perceived stress over 30 days [6]. Cognitive performance was assessed using CNS Vital Signs, a validated digital testing battery. Both ashwagandha groups outperformed placebo on cognitive flexibility, visual memory, reaction time, psychomotor speed, and executive functioning (p < 0.05 for each). Cortisol levels also fell in both ashwagandha groups over time, with the 225 mg group showing significant reductions as early as day 15.
The study didn’t include participants with clinical cognitive impairment, these were stressed but otherwise healthy adults. That matters. What it suggests is that the cognitive benefits may be partly mediated through stress reduction: lower cortisol, better sleep, reduced anxiety, and as those improve, cognitive performance follows. The brain isn’t being “boosted” in isolation; rather, the conditions that were suppressing it are being lifted.
A 2020 systematic review of ashwagandha’s clinical use for cognitive dysfunction identified five RCTs meeting inclusion criteria [7]. Across a heterogeneous range of populations, including older adults with mild cognitive impairment and adults with certain psychiatric conditions, ashwagandha extract consistently improved performance on cognitive tasks, executive function, attention, and reaction time. The authors noted it was well tolerated with good adherence and minimal side effects.
Evidence grade: Promising, This is an RCT, but it’s a small pilot study (n=40). Findings are encouraging but need replication at scale.
A 2025 double-blind, placebo-controlled pilot study specifically enrolled 40 adults with mild cognitive impairment (MCI), a condition where memory and thinking problems exceed what’s expected for age, but don’t yet meet criteria for dementia [1, 8]. Participants received 250 mg/day of a standardised ashwagandha extract (Somin-On™) or placebo for 60 days.
The results were notable for a pilot study. On the Wechsler Memory Scale, ashwagandha-treated participants showed significant improvements in immediate memory, general memory, working memory, and visuospatial processing compared to placebo at both 30 and 60 days. Montreal Cognitive Assessment (MoCA) scores improved by 7.83% at 30 days and 14.77% at 60 days from baseline. MMSE scores improved by 9.26% at 30 days and 19.21% at 60 days. On a visuospatial test (Shepard Mental Rotation), the improvement was 31.67% from baseline by day 60.
These are meaningful numbers, but the sample size of 40 means we should hold them lightly. What makes them worth taking seriously is the use of multiple validated cognitive assessment tools, all pointing in the same direction. Replication in larger trials is the obvious next step.
Evidence grade: Early stage, The mechanistic work below is largely from animal studies. Directionally useful, but human trial confirmation is needed.
Animal research has helped researchers understand *why* ashwagandha might be doing what the human trials suggest. A 2024 mouse study using the 5xFAD model of Alzheimer’s disease found ashwagandha improved spatial memory, reduced anxiety-like behaviour, and attenuated neuroinflammation and oxidative stress [9]. This is an Alzheimer’s mouse model, so extrapolating to humans requires significant caution, but the mechanisms identified (reduced beta-amyloid burden, lower neuroinflammation, antioxidant effects) are biologically plausible pathways.
A 2025 animal study specifically explored how ashwagandha protects against the cognitive impairment caused by sleep deprivation, a highly relevant model given that anxiety and poor sleep so frequently co-occur [3]. The study found ashwagandha worked through GABAergic pathways and antioxidant mechanisms to preserve memory function in sleep-deprived rats.
A 2024 rat study tested ashwagandha on an experimental model of PTSD, finding it attenuated anxiety-related behaviour in a dose-dependent manner, with effects comparable to fluoxetine (an SSRI) [14]. It also reversed elevated inflammatory markers (IL-6) and oxidative stress in both the hippocampus and prefrontal cortex, two brain regions central to both emotional regulation and cognitive performance.
A 2022 clinical pharmacology review synthesised both animal and human findings, concluding that ashwagandha’s benefits likely arise from a combination of neuroplasticity induction, antioxidant and anti-inflammatory effects, and modulation of GABA, glutamate, and serotonergic neurotransmitter systems [10]. The review also noted evidence for the presence of additional, as yet unidentified active compounds beyond the known withanolides, suggesting the herb’s effects may be even more complex than current research captures.
This is important, and we’re not going to gloss over it.
Sample sizes are consistently small. Most human trials involve fewer than 100 participants. The meta-analysis pooling nine RCTs reached 558 people total, which is progress, but we’re not yet in the territory of large-scale, long-duration trials that would allow confident clinical recommendations [15].
Study duration is short. The longest human trials reviewed here ran for 84 days [4]. We don’t yet know whether ashwagandha’s benefits persist or accumulate over months and years of use, or whether they plateau or diminish.
Formulations vary enormously. Somin-On™, Zenroot™, NooGandha®, and various unbranded root extracts all appear in the research, with different withanolide concentrations, extraction methods, and doses ranging from 125 mg to 600 mg/day [1, 4, 6, 13]. This makes it genuinely difficult to determine an optimal dose or formulation, and results across studies aren’t always directly comparable [11].
The causality question is unresolved. Does ashwagandha improve cognition by reducing anxiety and stress, does it have direct neuroprotective effects, or both? Human trial evidence cannot yet cleanly separate these pathways [6, 7].
Potential withdrawal effects have been flagged. A 2025 case report noted possible withdrawal-like effects upon discontinuing ashwagandha, including anxiety and insomnia [5]. This is a single case report, the very weakest form of clinical evidence, but it’s worth knowing that this possibility has been raised. It doesn’t suggest ashwagandha is dangerous, but it does suggest that if you choose to discontinue, tapering rather than stopping abruptly might be sensible.
Most mechanistic work is in animals. The elegant mechanistic picture, GABAergic modulation, neuroplasticity, anti-inflammatory effects, is largely derived from rodent studies [3, 9, 14]. These mechanisms are biologically plausible and consistent with the human trial results, but they are not confirmed in human neuroscience.
The 2024 meta-analysis noted mild to moderate adverse events in four of the nine included studies [15]. These weren’t serious, but they’re a reminder that “natural” doesn’t automatically mean “harmless for everyone.” Ashwagandha has known interactions with thyroid medications and sedatives, and pregnant women are generally advised to avoid it, topics that fall beyond the scope of this research but are worth being aware of.
Here’s what a sensible, well-informed person should do with all of this.
The evidence for ashwagandha’s effect on stress and anxiety is genuinely among the better-supported in the supplement world, multiple RCTs, a meta-analysis with consistent direction, and measurable effects on both subjective and objective markers like cortisol and heart rate variability [15, 13, 4]. For a supplement that has been in use for thousands of years and appears well-tolerated in human trials, that’s a meaningful body of support.
The cognitive angle is more nuanced. The most compelling interpretation of the current evidence is that ashwagandha helps the stressed, anxious brain function closer to its actual capacity, by reducing the cortisol load, improving sleep, and calming the neural noise that makes memory and focus so difficult when you’re chronically overwhelmed [6, 7]. Whether it also has direct neuroprotective effects in humans is genuinely uncertain, though the animal research and the MCI pilot study [1] make it a question worth watching closely.
In practical terms:
– If you’re in the 40-65 age bracket, experiencing elevated stress or anxiety, noticing that your memory and focus feel worse than they used to, and you’re not taking thyroid medication or sedatives, ashwagandha is a reasonable supplement to consider. The evidence supports it more than most things you’ll find on a health food shelf.
– Doses used in human trials range from 125 mg to 600 mg/day, with effects seen at lower doses and stronger cortisol reduction at higher doses [13]. A dose in the 250–500 mg range, from a standardised extract with a specified withanolide content, is where most positive human trial results cluster.
– Give it at least 8 weeks. Significant improvements in stress and sleep were seen at 4 weeks in some studies, but cognitive benefits in the MCI trial continued improving through 60 days [1, 13].
– It’s not a replacement for good sleep, regular movement, and managing the sources of stress in your life. But if you’re doing those things and still struggling, the evidence suggests ashwagandha may genuinely help, not by performing miracles, but by taking enough edge off the stress response that your brain can start doing its job properly again.
– If you decide to stop taking it, consider tapering rather than stopping abruptly, given the single case report of withdrawal-like effects [5]. This is cautious advice based on limited evidence, but it costs nothing to be gradual.
The bottom line: ashwagandha is one of those rare cases where traditional use, plausible biological mechanisms, and emerging clinical evidence are all pointing in the same direction. It doesn’t cure cognitive decline. But the case that chronic anxiety drives cognitive impairment, and that ashwagandha may meaningfully address the former, with downstream benefits to the latter, is more credible than most supplement claims you’ll encounter. Watch this space as larger, longer trials emerge.
[1] Effect of ashwagandha (Somin-On™) in adults with mild cognitive impairment (2025). DOI: 10.1177/02698811251324377 | https://pubmed.ncbi.nlm.nih.gov/40099725/
[2] Ashwagandha: Mental health, sleep quality and cognitive function review (2025). DOI: 10.3390/nu17132143 | https://pubmed.ncbi.nlm.nih.gov/40647248/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12252077/
[3] A Novel Ashwagandha Formulation and GABAergic pathway in sleep deprivation-induced cognitive dysfunction in rats (2025). DOI: 10.3390/biom15050710 | https://pubmed.ncbi.nlm.nih.gov/40427603/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12109121/
[4] A New Ashwagandha Formulation (Zenroot™) Alleviates Stress and Anxiety Symptoms While Improving Mood and Sleep Quality: A Randomized, Double-Blind, Placebo-Controlled Clinical Study (2025). DOI: 10.1007/s12325-025-03327-z | https://pubmed.ncbi.nlm.nih.gov/40875185/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12474591/
[5] Unmasking Potential Withdrawal Effects of Ashwagandha: A Case Report and Review (2025). DOI: 10.7759/cureus.83577 | https://pubmed.ncbi.nlm.nih.gov/40476122/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12139691/
[6] Efficacy of Withania somnifera supplementation on adult’s cognition and mood (2022). DOI: 10.1016/j.jaim.2021.08.003 | https://pubmed.ncbi.nlm.nih.gov/34838432/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8728079/
[7] A systematic review of the clinical use of Withania somnifera (Ashwagandha) to ameliorate cognitive dysfunction (2020). DOI: 10.1002/ptr.6552 | https://pubmed.ncbi.nlm.nih.gov/31742775/
[8] Effect of ashwagandha (Somin-On™) in adults with mild cognitive impairment, pilot RCT (2025). DOI: 10.1177/02698811251324377 | https://pubmed.ncbi.nlm.nih.gov/40099725/
[9] Withania somnifera (Ashwagandha) Improves Spatial Memory, Anxiety and Depressive-like Behavior in the 5xFAD Mouse Model of Alzheimer’s Disease (2024). DOI: 10.3390/antiox13101164 | https://pubmed.ncbi.nlm.nih.gov/39456417/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11504317/
[10] Potential clinical applications of Ashwagandha (Withania somnifera) in neuropsychiatry (2022). DOI: 10.1080/17512433.2022.2121699 | https://pubmed.ncbi.nlm.nih.gov/36062480/
[11] Effects of Withania somnifera (Ashwagandha) on stress, anxiety, depression and insomnia: review (2021). DOI: 10.2174/1570159X19666210712151556 | https://pubmed.ncbi.nlm.nih.gov/34254920/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8762185/
[12] An alternative treatment for anxiety: a systematic review of human trial results reported for the Ayurvedic herb ashwagandha (Withania somnifera) (2014). DOI: 10.1089/acm.2014.0177 | https://pubmed.ncbi.nlm.nih.gov/25405876/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270108/
[13] Adaptogenic and Anxiolytic Effects of Ashwagandha Root Extract in Healthy Adults: A Double-blind, Randomized, Placebo-controlled Clinical Study (2019). DOI: 10.7759/cureus.6466 | https://pubmed.ncbi.nlm.nih.gov/32021735/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6979308/
[14] Amelioration by Withania somnifera of neurobehavioural and immunological markers in time dependent sensitization induced post traumatic stress disorder in rats (2024). DOI: 10.4103/ijp.ijp_825_22 | https://pubmed.ncbi.nlm.nih.gov/38454585/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11001169/
[15] Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis (2024). DOI: 10.1016/j.explore.2024.103062 | https://pubmed.ncbi.nlm.nih.gov/39348746/
This article is for informational purposes only and does not constitute medical advice. Food supplements should not be used as a substitute for a varied and balanced diet and healthy lifestyle. If you are pregnant, breastfeeding, taking medication or have a medical condition, consult your doctor before taking any supplement. These statements have not been evaluated by the Food and Drug Administration (FDA) or the Medicines and Healthcare products Regulatory Agency (MHRA). This product is not intended to diagnose, treat, cure, or prevent any disease.
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