Phosphatidylserine

Phosphatidylserine (PS) is a phospholipid, one of the fats that build the membrane around your brain cells, and that membrane role is why it has been studied for memory for decades. But the evidence is modest, and there is a wrinkle that matters: the early trials and the pills on the shelf today are not made the same way. The original cognitive studies in the late 1980s and early 1990s used PS pulled from bovine (cow) brain cortex (BC-PS). That form is no longer sold over the counter in the US, because mad-cow (BSE) concerns pushed the whole market to plant-derived PS made from soy or sunflower. The plant-PS trials are smaller, and the effects are softer than the original cow-brain work. The FDA looked at all of this in 2003 and allowed a qualified health claim that PS "may reduce the risk of dementia and cognitive dysfunction in the elderly," with the explicit caveat that the supporting evidence is "limited and inconclusive." That caveat is the honest summary.

The memory case rests on a handful of trials. Crook 1991 (Neurology) gave 149 adults with age-associated memory complaints 100mg of cow-brain PS three times daily for 12 weeks and found gains on learning and everyday memory tasks, strongest in the people who started out worst. The plant-PS replications are weaker. Kato-Kataoka 2010 ran a 6-month double-blind trial in 78 elderly Japanese adults with memory complaints at 100mg or 300mg/day of soy-PS and saw delayed verbal recall improve in the lowest-baseline subgroup, with no clear dose-response. Vakhapova 2010 used a PS-DHA conjugate (PS bound to an omega-3, not plain PS) in 157 non-demented elderly adults for 15 weeks and reported better immediate verbal recall, mostly in the higher-functioning subgroup. None of these show large effects, and the after-the-fact subgroup splits do most of the heavy lifting.

The athlete-cortisol story is a separate question, and it runs at much higher doses. Monteleone 1992 gave healthy men 800mg/day of cow-brain PS for 10 days and saw blunted ACTH and cortisol (the main stress hormones) responses to a cycling stress test. Starks 2008 gave trained men 600mg/day of soy-PS for 10 days and reported a 39% drop in peak cortisol plus a higher testosterone-to-cortisol ratio after moderate cycling. The mechanism is plausible, but the trials are tiny (under 10 men each), short, and not replicated at scale. Read it as an early signal in athletes, not a settled finding for everyday stress.

The kids-and-ADHD signal is also early. Hirayama 2014 randomized 36 unmedicated children aged 4-14 to 200mg/day of soy-PS or placebo for 2 months and reported better ADHD symptoms and short-term auditory memory. A 2021 review and meta-analysis (Bruton et al.) pooled three trials (216 children) and found a real effect on inattention specifically, but not on overall ADHD or hyperactivity-impulsivity, and the overall evidence quality was low. PS is not a stand-in for first-line ADHD treatment, but the inattention signal is solid enough to deserve bigger trials.

So where does that leave you. If you are an older adult with memory complaints, PS is a low-risk thing to try at 100mg three times daily, as long as you go in knowing the benefit is modest and shows up most in people who started out lower. If you are an athlete chasing the cortisol response to heavy training, 600-800mg/day is worth a test, with the caveat that there is no strong evidence it does anything for general-population stress. Either way, look for Sharp-PS (soy) or Sharp-PS GREEN (sunflower) on the label, the standardized forms behind the modern trials. A bottle that just says "phosphatidylserine complex" with no branded extract named is harder to judge.