Ashwagandha And Chronic Stress — Protecting Your Brain Long-Term

Ashwagandha and Chronic Stress: What It’s Actually Doing to Your Brain Long-Term

What if the most damaging thing happening to your brain right now isn’t a dramatic event, a fall, a diagnosis, a sudden shock, but something far quieter? What if it’s the low hum of everyday stress that’s been running in the background for years, slowly reshaping the architecture of your mind? And what if a herb that Ayurvedic physicians have been prescribing for over 3,000 years is genuinely doing something measurable about it?

These aren’t rhetorical questions. From the 1.77 million research papers Vitacuity has analysed, we selected 15 of the most relevant studies on ashwagandha and stress, and what they reveal about the relationship between chronic stress and long-term brain health is both sobering and, ultimately, genuinely encouraging.

The Science Behind Ashwagandha: How Chronic Stress Damages the Brain, and What Ashwagandha Does About It

Before we get to ashwagandha, we need to understand what chronic stress actually does to your brain. Because it isn’t just a feeling, it’s a biological process with measurable consequences.

When you’re under stress, your body activates the HPA axis, the hypothalamic-pituitary-adrenal system. Think of this as your internal alarm system. It releases cortisol, your primary stress hormone, which prepares the body for immediate threats. That’s fine in short bursts. The problem is when the alarm never turns off [7].

Sustained high cortisol is corrosive to the brain. It causes inflammation, accelerates oxidative stress (a form of cellular “rusting”), and is particularly damaging to the hippocampus, the region of the brain most critical for memory formation and recall [15]. Research also links chronic stress to the accumulation of tau protein, the same pathological protein associated with Alzheimer’s disease [15]. In short, years of unmanaged stress aren’t just exhausting. They may be quietly accelerating cognitive decline.

Ashwagandha, known botanically as *Withania somnifera*, contains a family of active compounds called withanolides. These appear to work through several mechanisms simultaneously: calming the HPA axis to lower cortisol output, reducing inflammatory markers in the brain and body, protecting neurons from oxidative damage, and, critically, supporting a molecule called BDNF (brain-derived neurotrophic factor), which you can think of as a kind of fertiliser for brain cells. BDNF supports the growth, maintenance, and survival of neurons. Chronic stress suppresses it. Ashwagandha, in both animal and human studies, appears to restore it [2].

Key Finding 1: It Genuinely Reduces Perceived Stress, Across Multiple Doses

The evidence here is reasonably strong by supplement standards. A randomised, double-blind, placebo-controlled trial published in *Nutrients* (2024) enrolled 131 adults with mild to moderate chronic stress and tested three doses of aqueous ashwagandha extract: 125 mg, 250 mg, and 500 mg daily for 8 weeks. All three doses significantly reduced scores on the 14-item Perceived Stress Scale (PSS) compared to placebo, and the effect was dose-dependent, meaning higher doses produced greater reductions. Importantly, the mechanism appeared to be genuine modulation of the HPA axis rather than a placebo effect, with measurable changes in biochemical stress markers [7].

A separate 84-day randomised controlled trial published in *Advances in Therapy* (2025) tested 125 mg of a standardised ashwagandha formulation (Zenroot™) containing 1.5% withanolides. Ninety adults with mild to moderate stress were randomised to either the supplement or placebo. The ashwagandha group showed significant improvements in PSS scores from day 28 onwards, alongside objective improvements in heart rate variability (HRV), a physiological measure of how well your nervous system is managing stress, and reductions in skin conductance response, another objective stress marker. Sleep quality (measured by the Pittsburgh Sleep Quality Index) and mood (measured by the Profile of Mood States) also improved significantly [5].

Evidence grade: Promising to Strong. Multiple RCTs with consistent findings. Sample sizes are modest (under 130 in each study), and most trials run for 8–12 weeks rather than years. But the direction of evidence is consistent.

Key Finding 2: It Improves Memory, Focus and Cognitive Performance in Stressed Adults

This is perhaps the most directly relevant finding for anyone reading this in their 40s, 50s or 60s and noticing that stress seems to be making your thinking fuzzy.

A double-blind, placebo-controlled study published in *Evidence-Based Complementary and Alternative Medicine* (2021) enrolled 130 healthy but cognitively stressed adults aged 20–55, giving them a standardised ashwagandha slow-release (SR) capsule once daily for 90 days. Using the Cambridge Neuropsychological Test Automated Battery (CANTAB), a validated, objective cognitive test, the ashwagandha group showed significantly improved recall memory compared to placebo. The first-attempt memory score was 12.9 ± 6.7 in the ashwagandha group versus 10.1 ± 6.3 in the placebo group, and total error rates in pattern recall were meaningfully lower (17.5 ± 23.3 versus 27.7 ± 23.6). Perceived stress scores (PSS-10) also dropped significantly: 13.0 ± 5.0 in the ashwagandha group versus 18.7 ± 4.6 in placebo at the final visit [14].

A second cognition-focused study published in the *Journal of Ayurveda and Integrative Medicine* (2022) randomised 60 stressed adults to receive 400 mg ashwagandha daily, 225 mg daily, or placebo for 30 days. Using CNS Vital Signs cognitive testing, the ashwagandha groups outperformed placebo on cognitive flexibility, visual memory, reaction time, psychomotor speed, and executive functioning. Cortisol reductions were also observed, significantly so in the 225 mg/day group [13].

An earlier pilot study from 2017, published in the *Journal of Dietary Supplements*, similarly found that ashwagandha root extract improved memory and cognitive function in adults with mild cognitive impairment [10].

Evidence grade: Promising. Results are consistent, and the use of objective cognitive testing (rather than self-report alone) adds meaningful credibility. However, most trials run under 90 days and involve relatively small samples.

Key Finding 3: It Appears to Protect the Brain at a Cellular Level, Particularly the Hippocampus

This is where the science gets genuinely fascinating, though we need to be honest that most of this evidence comes from animal and laboratory studies rather than human trials.

A 2025 study published in the *Journal of Ethnopharmacology* investigated what ashwagandha root extract does to brain cells under chronic stress conditions. In mouse models of unpredictable chronic mild stress (UCMS), ashwagandha extract reduced hippocampal cell loss, meaning the region of the brain critical for memory was physically better preserved in stressed animals that received the extract. The extract also restored levels of BDNF (the brain’s “growth factor”), reduced stress hormones including corticosterone, and significantly lowered inflammatory proteins including IL-6, IL-1β and TNF-α [2].

In the same study, laboratory experiments on brain cells exposed to corticosterone (the animal equivalent of cortisol) showed that ashwagandha extract and its active compound withanolide A prevented the oxidative damage and cellular stress that cortisol exposure normally causes [2].

A 2020 review in the *Journal of Ethnopharmacology* covering neurodegenerative diseases noted that ashwagandha extracts and its constituent compounds show neuroprotective properties in preclinical models of Alzheimer’s, Parkinson’s and Huntington’s disease, with protective mechanisms including restoration of mitochondrial function, reduction of inflammation, and mitigation of oxidative stress [9].

Evidence grade: Early stage for neuroprotection in humans. The cellular and animal data are compelling and mechanistically coherent. But the translation to humans hasn’t been fully demonstrated in long-term trials. This is honest-to-goodness “watch this space” territory, the science is pointing in a hopeful direction.

Key Finding 4: It Lowers Cortisol, and This Has Been Measured Objectively

One of the most important findings across the ashwagandha literature is that it doesn’t just make people *feel* less stressed, it measurably reduces cortisol levels in the blood and saliva.

The 12-month safety and observational study published in *Phytotherapy Research* (2025), the longest duration study in our dataset, enrolled 191 adults aged 18–65 and monitored them for a full year taking standardised ashwagandha root extract. Serum cortisol decreased significantly (p < 0.001) over the course of the year. Crucially, liver function (alanine and aspartate transaminase levels) remained stable throughout, confirming safety at long-term doses. Overall, 68.7% of participants showed measurable improvement on the Clinical Global Impression scale, with the most notable improvements in those aged 50 and over [4].

In the 8-week dose-response RCT mentioned above, modulation of the HPA axis (the cortisol-producing system) was identified as the primary mechanism of action at all three doses tested [7].

In the 30-day cognition trial, both ashwagandha doses produced cortisol reductions over time, with the 225 mg/day group achieving statistical significance from day 0 to day 15 to day 30. The placebo group, by contrast, showed a non-significant *increase* in cortisol over the same period [13].

Evidence grade: Promising to Strong. Cortisol reduction has been replicated across multiple trials using objective blood and saliva testing. The 12-month observational study [4] is particularly notable for its duration, though it lacks a placebo control.

Key Finding 5: It Supports Healthy Ageing Beyond Just Stress, Including Muscle, Sleep and Inflammation

A comprehensive 2025 review in *Biogerontology* synthesised the broader anti-ageing evidence for ashwagandha. The review highlighted that clinical trials have demonstrated improvements in muscle strength and size, cardiorespiratory fitness, hormonal balance (including significant increases in free and total testosterone, p < 0.05, confirmed in the 12-month observational study [4]), skin health, and sleep quality in older adults [1].

The review also highlighted ashwagandha’s effects on inflammaging, a term for the low-grade chronic inflammation that accompanies ageing and is increasingly understood as a driver of cognitive decline and neurodegenerative disease. Ashwagandha appears to lower C-reactive protein (CRP), a key marker of this systemic inflammation [1].

The same review notes promising preclinical data suggesting neuroprotective potential in models of Alzheimer’s and Parkinson’s disease, and points to ashwagandha’s apparent ability to enhance telomerase activity, an enzyme involved in maintaining the protective caps (telomeres) on chromosomes that govern cellular longevity [1].

Evidence grade: Promising for sleep and inflammation (multiple trials); Early stage for telomerase and neuroprotection in humans.

What We Don’t Know Yet

Here’s where we need to be honest, and this matters if you’re making decisions about what to take.

The long-term brain protection question is still open. While the stress-reduction and cortisol-lowering effects have been replicated across multiple RCTs, the translation to *actual* long-term protection against cognitive decline or neurodegenerative disease in humans has not been demonstrated. The animal and cell studies are mechanistically compelling, ashwagandha really does appear to protect hippocampal cells and restore BDNF in stressed mice, but mice are not humans, and we don’t yet have long-term RCTs in humans tracking cognitive decline over years or decades [2][9].

Dose and formulation vary enormously across studies. The trials in our dataset used doses ranging from 125 mg to 600 mg daily, different parts of the plant (root only vs. root and leaf), different extraction methods (aqueous vs. ethanolic), and different standardisation levels (withanolide content from 1.5% to higher). This makes it difficult to give a definitive “optimal dose” recommendation [7][5][13].

Most trials are short. With the exception of the 12-month observational study [4], almost all RCTs run for 8–12 weeks. That’s long enough to measure stress and mood, but far too short to draw conclusions about brain protection over decades.

Thyroid interactions need flagging. The 12-month study monitored thyroid function specifically, it remained stable, which is reassuring [4]. But ashwagandha is known in some cases to influence thyroid hormone levels. If you have a thyroid condition or take thyroid medication, this is worth discussing with your GP.

The saffron paper [15] in our dataset, while relevant to the chronic stress-Alzheimer’s link, is focused on saffron rather than ashwagandha. We’ve included it because it provides important context for how chronic stress and cortisol connect to Alzheimer’s pathology, but we want to be clear that the saffron findings don’t transfer directly to ashwagandha.

The Final Takeaway

Let’s think about this like a sensible, well-informed friend would.

You are, in all likelihood, under more chronic stress than is good for your brain. If you’re in your 40s, 50s or 60s, you’ve probably been carrying that stress for years. The research is clear that this has measurable biological consequences, elevated cortisol, hippocampal stress, inflammation, suppressed BDNF. These aren’t abstract risks. They’re the biological footprint of modern life.

Ashwagandha has a genuinely meaningful body of evidence behind it, multiple randomised controlled trials showing it reduces cortisol, lowers perceived stress, improves sleep quality, and measurably improves cognitive performance in stressed adults. These aren’t huge trials, and they’re not running for decades. But the findings are consistent, the mechanisms are coherent, and the safety profile, including a 12-month clinical study, is reassuring [4].

What should you actually do?

A standardised root extract at 300–500 mg per day is the dose range with the most consistent human evidence, though doses as low as 125 mg daily have shown measurable effects in some trials [5][7]. Look for a product standardised to its withanolide content, this is the active compound class. Taking it daily, consistently, for at least 8 weeks gives the trials’ timelines to play out.

Ashwagandha is not a substitute for sleep, exercise, or reducing genuine sources of stress in your life. But as a daily supplement for someone in their 40s–60s who is managing real-world stress loads? The risk-benefit calculation is straightforward. It’s safe at normal doses, the 12-month observational study with 191 participants found only 18 mild adverse events, all of which resolved without intervention [4]. It addresses one of the most well-documented drivers of cognitive ageing (cortisol and HPA dysregulation). And the cost is modest.

If you have a thyroid condition, are pregnant, or are on immunosuppressant medications, speak to your GP first. For everyone else: the evidence is good enough to act on, and the risks at normal doses are low. Don’t wait for the perfect 30-year trial before protecting your brain from something that’s happening to it right now.

References

[1] Enhancing healthspan with Ashwagandha (*Withania somnifera*): a comprehensive review of its multifaceted geroprotective benefits (2025). DOI: 10.1007/s10522-025-10320-0 | https://pubmed.ncbi.nlm.nih.gov/40921883/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12417257/

[2] Ashwagandha (*Withania somnifera* (L.) Dunal) root extract containing withanolide A alleviates depression-like behavior in mice by enhancing the brain-derived neurotrophic factor pathway under unexpected chronic mild stress (2025). DOI: 10.1016/j.jep.2024.119224 | https://pubmed.ncbi.nlm.nih.gov/39674356/

[3] Ashwagandha (*Withania somnifera*), mental health, sleep quality, cognitive function, anxiety, stress review (2025). DOI: 10.3390/nu17132143 | https://pubmed.ncbi.nlm.nih.gov/40647248/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12252077/

[4] Safety of 12-Months Administration of Ashwagandha (*Withania somnifera*) Standardized Root Extract in Healthy Adults: A Prospective, Observational Study (2025). DOI: 10.1002/ptr.70096 | https://pubmed.ncbi.nlm.nih.gov/41063394/

[5] 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/

[7] Effects of *Withania somnifera* (aqueous root and leaf extract) on chronic stress, randomised, double-blind, placebo-controlled dose-response study (2024). DOI: 10.3390/nu16091293 | https://pubmed.ncbi.nlm.nih.gov/38732539/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11085552/

[9] Neurodegenerative diseases and *Withania somnifera* (L.): An update (2020). DOI: 10.1016/j.jep.2020.112769 | https://pubmed.ncbi.nlm.nih.gov/32240781/

[10] Efficacy and Safety of Ashwagandha (*Withania somnifera* (L.) Dunal) Root Extract in Improving Memory and Cognitive Functions (2017). DOI: 10.1080/19390211.2017.1284970 | https://pubmed.ncbi.nlm.nih.gov/28471731/

[11] Adaptogenic activity of *Withania somnifera*: an experimental study using a rat model of chronic stress (2003). DOI: 10.1016/s0091-3057(03)00110-2 | https://pubmed.ncbi.nlm.nih.gov/12895672/

[12] Body Weight Management in Adults Under Chronic Stress Through Treatment With Ashwagandha Root Extract: A Double-Blind, Randomized, Placebo-Controlled Trial (2017). https://pubmed.ncbi.nlm.nih.gov/27055824/

[13] 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/

[14] Efficacy and Safety of Ashwagandha Root Extract on Cognitive Functions in Healthy, Stressed Adults: A Randomized, Double-Blind, Placebo-Controlled Study (2021). DOI: 10.1155/2021/8254344 | https://pubmed.ncbi.nlm.nih.gov/34858513/ | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8632422/

[15] Association between chronic stress and Alzheimer’s disease: Therapeutic effects of Saffron (2021). DOI: 10.1016/j.biopha.2020.110995 | https://pubmed.ncbi.nlm.nih.gov/33232931/

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