Primary Research · 1991
Effect of phosphatidylserine in age-associated memory impairment
Crook TH, Tinklenberg J, Yesavage J, et al. · Neurology, 1991
Key finding
12-week double-blind RCT (n=149) in age-associated memory impairment found 300mg/day bovine-source phosphatidylserine improved learning and memory vs placebo — one of the landmark early cognition trials.
Abstract
PubMed · PMID 2041575 →The case-control method was applied in order to test how various types of diet as well as past diseases, tobacco smoking and occupational exposure may affect the risk of incidence of corpus uteri cancer in the population of natives and among immigrant women. The highest risk of incidence was noted in the group of natives persistently using a diet rich in meat, animal fat, amylum meals and sugar but lacking raw vegetables. Such a high risk was not observed in the group of immigrant women what might be caused by more frequent change of the type of diet. Some past diseases (arterial hypertension, diabetes, diseases of organs of reproduction and urinary system) do affect a relatively high risk of corpus uteri carcinoma in both populations. However, no noteworthy results have been obtained in the risk of corpus uteri carcinoma as far as tobacco smoking and occupational exposure are concerned.
Abstract sourced from PubMed, a database of the U.S. National Library of Medicine. Displayed in the authors’ own words for context; our critique is in the sections below.
About the supplement
Phosphatidylserine (PS)
Dose · mechanism · evidence grade · safety →
Read the full paper
How to read a study like this
The same questions worth asking about any research paper, not just this one. Worth a minute even if you trust the grade.
Who was studied, and do you resemble them?
Supplement effects often depend on baseline status. Vitamin D helps people who are deficient; iron helps people who are anemic. A result in people unlike you may not apply to you.
What was measured, and does it matter in daily life?
A study that shows a blood marker moved isn't the same as a study that shows people felt or functioned better. Ask what the outcome means in practice.
How large was the effect — not just whether it was significant.
'Statistically significant' only means the effect is unlikely to be zero. It doesn't tell you the effect is large enough to notice. Look for effect sizes, not just p-values.
Who paid for the trial, and what did they stand to gain?
Industry-funded trials are several times more likely to report positive results than independent ones. It's not usually fraud — it's subtle design and reporting choices. Weight accordingly.
Has anyone else replicated this?
Single positive trials are hypotheses. Replication by independent groups is what turns a hypothesis into reliable evidence. If the only positive trial is the one you're reading, wait.
Does the dose in the trial match what's being sold?
Supplement marketing routinely cites trials that used 5–10× the dose in the product. If the effective dose was 2 g/day and the capsule has 200 mg, expect roughly no effect.
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