A new Australian study suggests that increased intake of omega-3 fatty acids may reduce depressive symptoms for older people with mild cognitive impairment, and lower their risk of digressing to dementia. At the same time, a controversially discussed review found no benefits associated with omega-3 fatty acid supplementation on cognitive function in cognitively healthy older people.
The randomized controlled trial investigated potential benefits of supplementing a diet with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for depressive symptoms, better quality of life (QOL) and improved cognition for elderly people with mild cognitive impairment (MCI) (1). A total of 50 people aged over 65 years with MCI were divided into groups and given supplements rich in EPA (1.67 g EPA + 0.16 g DHA per day), DHA (1.55 g DHA + 0.40 g EPA per day) or the omega-6 fatty acid linoleic acid (LA; 2.2 g per day) for a period of 6 months. The study results showed that, compared with the LA group, geriatric depres-sion symptoms improved significantly among people in the EPA and DHA groups. Verbal fluency also got better in the DHA group. Reduced symptoms of depression were correlated with increased DHA plus EPA intakes. Improved self-reported physical health was associated with increased DHA intakes, although there were no clinical effects on other cognitive or QOL parameters.
The researchers concluded that increased intakes of DHA and EPA may be beneficial for the mental health of elderly people with MCI. Increasing omega-3 fatty acid intake may reduce depressive symptoms and the risk of digressing to dementia. These findings require larger clinical trials need to be confirmed, said the resear-chers.
In a systematic review, published at the same time, 3 randomized controlled trials involving 3,536 cognitively healthy participants over the age of 60 years were analyzed to see whether omega-3 supplements did prevent cognitive decline and dementia (2). The data analysis showed no effect on cognitive function. Expert criticized that the studies evaluated in the review had serious flaws: while the largest trial focused on the prevention of cardiovascular diseases and was not designed to measure cognition (Geleijnse J. M. et al. 2011), the two smaller studies were short and used doses that were too low to show an effect (Dangour A. D. et al. 2010) or included participants who already had high levels of DHA in their blood to begin with (van de Rest O. et al. 2008).