An omega-3 fatty acid plentiful in fish oil boosts the ability of healthy young adults - whose brains are already at their peak levels of speed and performance - to hold several items in memory for a short time, a study has found.
The study is the first to suggest fish oil might enhance cognitive performance in healthy people by boosting their working memory.
The latest research adds to evidence of fish oil's beneficial neuropsychiatric effects: Supplementation with the docosahexaenoic acid, or DHA, in fish oil has been shown to improve the effectiveness of antidepressants, to improve focus in those with attention deficits, to delay the development of psychosis in those at risk of schizophrenia, and to help shore up declining memory in healthy older adults.
But the latest research failed to uncover how the polyunsaturated fatty acid works to promote wide-ranging benefits.
In the study, published last week in the open-access journal Public Library of Science, or PLoS, 11 healthy Caucasian adults with an average age of 22 underwent a six-month supplementation of their diet with fish oil (750 mg per day of DHA and 930 mg per day of eicosapentaenoic acid, or EPA).
Researchers measured before-and-after levels of omega-3 acids in the red-blood-cell membranes of subjects and put them through a battery of tests to gauge the strength of their working, or short-term, memory. After six months of supplementation with fish oil, the youthful subjects did 23 percent better on a key challenge to working memory: the ability to recall, given a list of several items, which one was mentioned three items back.
The mystery of how omega-3s work to rev up the brain, however, remains intact.
A key object of the research was to determine whether omega-3 supplementation works by boosting the availability and function of the neurotransmitter dopamine in a key part of the brain.
The study authors used positron emission tomography, known as a PET scan, to look deep into the forebrain, to a region called the striatum, where dopamine is typically most plentiful. They hoped to detect whether fish oil supplementation would increase dopamine levels there, and whether such increases could be linked to better working-memory performance.
The supplements did indeed boost levels of DHA and EPA in subjects' blood, but not in their striata. Improved performance in subjects' working memory was linked to changes in blood levels of the fatty acids in fish oil, but that does little to explain how it works to improve cognition.
The authors of the study surmised perhaps fish oil improves cognition by reducing inflammation or boosting the strength of signals passing among brain cells, or by improving the availability of dopamine in other parts of the brain.