As the primary polyunsaturated fatty acid (PUFA) in the brain, DHA is responsible for neuronal functions that affect “learning, memory, auditory, and olfactory responses.” Because DHA status is dependent on dietary intake of this essential fatty acid, individuals who do not consume sufficient amounts may experience impaired cognition. Moreover, most research on the DHA-brain connection has occurred in populations at each end of the lifespan—children and older adults. Few studies have addressed DHA’s effects on healthy young adults. The current study investigates the effects of DHA on memory in this population, while also considering interaction effects for sex and apolipoprotein E genotype (APOE), two factors that have been shown to affect brain function.
Eighty-three men and 145 women aged 18–45 years old were selected for the placebo-controlled, double-blind study. All participants were healthy and none had consumed omega-3 fish oil supplements in the preceding six months before they were randomly assigned to either a DHA treatment (1.16 g DHA + 0.17 g EPA soft gel daily) or a placebo (sunflower oil) group. Episodic memory, working memory, attention, and processing speed were all measured using the Computerised Mental Performance Assessment System, among other test batteries.
Results of the six-month investigation revealed that DHA improved certain dimensions of memory, and that gender also regulated these effects. Specifically, episodic memory improved significantly in women who consumed DHA, compared to the placebo group, but this effect was not seen in men, whose reaction time of working memory appeared to benefit from DHA consumption. Attention and processing speed appeared largely unaffected. The effects of DHA consumption shown in this study support the view that DHA benefits the brain throughout life, not just in early childhood and old age.
Stonehouse W, Conlon C, Podd J, et al. DHA supplementation improved both memory and reaction time in healthy young adults. AJCN March 2013.