One hundred-twenty men and women (mean age, 65 years) with age-associated memory impairment were randomly assigned to receive, in double-blind fashion, either 1) placebo, 2) 300 mg/day of soy-derived phosphatidylserine, or 3) 600 mg/day of soy-derived phosphatidylserine for 12 weeks. Assessments were carried out at baseline, after 6 and 12 weeks of treatment, and 3 weeks after treatment was discontinued. Tests of learning and memory, choice reaction time, and planning and attention functions were administered at each assessment. Delayed recall and recognition of a previously learned word list were the primary outcome measures. No significant differences were found between treatment groups in any of the outcome variables. There were also no significant interactions between treatment and severity of memory complaints.

Comment: Phosphatidylserine derived from bovine brain has been shown in numerous studies to have a positive effect on cognitive function in people with age-related cognitive decline and in those with Alzheimer's disease. However, because of fears that cow-brain preparations could cause infectious diseases such as mad-cow disease, this product is not available in the United States. Soy-derived phosphatidylserine, which is commercially available, does not have the same chemical structure as the cow-derived product; consequently, these preparations may not have the same effects on brain function. The results of the present study suggest that the phosphatidylserine available in the US is not effective for prevention or treatment of cognitive decline.

Potentially beneficial treatments for this problem include Ginkgo biloba extract, vitamin B12, dehydroepiandrosterone, and lemon balm (see J Neurol Neurosurg Psychiatry 2003;74:863-866 for information regarding lemon balm).

Jorissen BL, et al. The influence of soy-derived phosphatidylserine on cognition in age-associated memory impairment. Nutr Neurosci 2001;4:121-134.