Ashwagandha Lifts Memory and Strength

More than a wellness trend: this Ayurvedic herb improves cognition and physical performance in adults

STUDY: Zhu X et al, Front. Pharmaco

STUDY TYPE: Systematic review and meta-analysis

FUNDING: Shenzhen Science and Technology Program; Sanming Project of Medicine in Shenzhen

Background

Ashwagandha (Withania somnifera) is an Ayurvedic root extract with anti-inflammatory and neuroprotective properties. It modulates stress hormones via the hypothalamic-pituitary-adrenal axis and promotes axonal regeneration, effects that have fueled interest in its cognitive and physical benefits. This meta-analysis takes a broad look at its effects.

The Study

• 20 randomized controlled trials, 1,249 adults, ages 18–75; most studies enrolled healthy adults
• Ashwagandha extract (225–675 mg/day, most commonly 600 mg/day) versus placebo
• Trial durations ranged from 7 days to 16 weeks; 8 weeks was most common
• Outcomes: memory, attention, executive function, visuospatial ability, testosterone, muscle strength, and body composition

Results

Memory improved with a moderate effect size (0.52). Attention and processing speed showed a smaller but consistent gain (effect size 0.29). Executive function also improved (0.42). Visuospatial ability improved modestly after removing one outlier study (0.39). Only one study assessed global cognition, so those findings are preliminary.

On the physical side, testosterone rose slightly (effect size 0.33), and muscle strength improved (0.58), but mainly in physically active individuals (1.03), not in untrained populations. Body weight and body fat didn’t change.

Side Effects

Ashwagandha has a clean safety record in these trials: side effects were mild and mostly gastrointestinal. There have been rare case reports of liver injury, although it also protects the liver.

Limitations

Most trials were small and short, with only a handful of studies per outcome. Preparation quality varied widely: withanolide content, the herb’s active compound, was inconsistently reported across studies, making comparisons difficult. Evidence certainty ranged from moderate to very low by GRADE criteria.

Practice Implications

1. The results are encouraging but preliminary. The cognitive gains are real by statistical standards, but the effect sizes are modest, the trials are short, and most participants were healthy adults, not patients with cognitive complaints.
2. Aim for a 600 mg/day of a standardized root extract (look for at least 5% withanolides) for 8 weeks is a reasonable trial, with realistic expectations. For safety, stick with lab-tested, standardized extracts like the ones here.
3. Learn how ashwagandha, combined with melatonin, improved sleep in a large trial.