Healthy 18- to 25-year-olds at the top of their "cognitive game" can enhance their working memory even further by increasing their intake of omega-3 polyunsaturated fatty acids (n-3 PUFA), a small study suggests.
"Working memory is critical for adaptive reasoning and problem solving," Bita Moghaddam, PhD, professor of neuroscience from the University of Pittsburgh in Pennsylvania, who worked on the study, told Medscape Medical News. "This is the first study that shows that a dietary supplement (or, in fact, any treatment) improves this important cognitive ability in highly functional healthy young adults."
The study showed a positive correlation between blood levels of n-3 PUFA and working memory "indicating that diet plays a role in the cognitive abilities of young healthy adults," Dr. Moghaddam said. "Diet is not just about weight but can have a fundamental influence on brain function even in young healthy individuals."
However, the mechanism for omega-3's cognitive benefits remains unclear, the study team says. Their primary hypothesis — that n-3 PUFA supplementation increases dopamine neurotransmission by increasing striatal vesicular monoamine transporter type 2 (VMAT2) — didn't pan out in this study.
But Dr. Moghaddam said the mechanistic aspect of the study was "limited" in that it looked only at a single target (VMAT2); "so it basically means other mechanisms must be important and we already have several targets in mind."
The study was published online October 3 in PLoS One.
Positive Correlations
Eleven healthy young adults underwent positron emission tomography (PET) using a selective VMAT2 PET tracer before and after 6 months of n3 PUFA supplementation (Lovaza, 2 g/d, containing docosahexaenoic acid, 750 mg/d, and eicosapentaenoic acid, 930 mg/d).
They also completed a standard working memory task (the "n-back" test) and analysis of red blood cell membrane fatty acid composition before and after supplementation.
Of note, said Dr. Moghaddam, presupplementation n-back test results correlated positively with plasma omega-3 levels (P = .009). "This means that the omega-3s they were getting from their diet already positively correlated with their working memory," she noted in a statement.
In addition, performance on the working memory task improved after 6 months of n-3 PUFA supplementation (P = .04).
In their paper, the researchers note that some prior studies have suggested n-3 PUFA deficiency is associated with impairment in mood and cognitive functioning. Some studies have also hinted that n-3 PUFA supplementation could have a role as adjunctive therapy in neuropsychiatric disorders, such as mood disorders, schizophrenia, and attention-deficit/hyperactivity disorder.
"Late adolescence to early adulthood (age 18-25 in our study) is a vulnerable age given that symptomatic onset of most psychiatric illnesses, including bipolar and schizophrenia, occurs in this period," Dr. Moghaddam told Medscape Medical News. "An omega-3 deficiency could contribute to this vulnerability."
Diet and Mental Abilities
Stephen Manuck, PhD, distinguished professor of health psychology and behavioral medicine at University of Pittsburgh, who was not involved in the study, told Medscape Medical News, "This study is important because, as much as we've begun to worry about eating habits in youth in order to forestall obesity, we still know very little about how components of diet affect mental abilities in early life."
"In addition, the brain undergoes a great deal of reorganization during adolescence, and does so in areas required for the type of memory performance measured here," Dr. Manuck said.
"It will be interesting in future research to determine if the gains in working memory ability seen in this study persist over time (perhaps because the added omega-3 fatty acids are supporting brain maturation at a critical time in development) or can be maintained only with continued omega-3 supplementation."
The study was supported by awards from the National Institute on Drug Abuse and American Reinvestment and Recovery Act of 2009. The authors and Dr. Manuck have disclosed no relevant financial relationships.
PLoS One. Published online October 3, 2012. Abstract
