Studies of the effects of phosphatidylserine (PS) on cognition have shown inconsistent results; some randomized controlled trials (RCTs) have found improvements with supplementation in only one or two subdomains (of several) within a given cognitive assessment tool, whereas other RCTs have found improvements in the overall score of the assessment tool used. However, most RCTs to date have had the limitation of a short duration for examining cognition, usually 1 to 3 months. More, and longer, trials are needed to clarify PS’s effects on cognition.
Several trials have been done on PS supplementation in older adults. One 1993 RCT of PS supplementation in older adults noted improvements in both cognition and withdrawal/apathy scores in the participants taking PS but no improvements in activities of daily living. While this early study is dated, it was quite large and long, with nearly 500 participants and a duration of 6 months.[1]
Unfortunately, more recent research hasn't clarified PS's potential cognitive benefits for older adults. One 15-week RCT of PS plus omega-3 fatty acids supplementation in older adults saw improvements in the supplemented participants on one of two measures of immediate recall, but not on 8 other measures of cognition. However, a newer RCT by the same researchers, which set out to measure slightly different outcomes and used a lower dose of PS, found improvements both in two subdomains and the overall score on one set of cognitive assessments, but no improvement on another cognitive assessment.[2][3] And, although a small 2-month pilot RCT of PS supplementation (plus phosphatidic acid, a precursor of PS) in people with Alzheimer's disease found that the participants who received supplements experienced a slower decline in 7 activities of daily living than those given a placebo, the participants did not have improvements in memory, mental status, or mood.[4]
The effects of PS supplementation on cognition have also been studied in young and middle-aged adults with no known health conditions, but much more research is needed. One small 2008 study found that 6 weeks of supplementation with 200 mg of PS did not affect any measures of cognitive function after a cognitively stressful task. However, the participants who’d taken PS did have slightly different EEG readings in the brain both before and after the test task, which might be indicative of higher levels of relaxation.[5] PS has also been studied in young and midlife adults in combination with Gingko biloba[6] and magnesium L-threonate;[7] while these studies found positive effects on memory, it's hard to say how much of the effects can be attributed to PS.