Omega-3 fatty acids linked to depression in elderly

Fatty acids may have a significant impact on mood in the elderly, say researchers in the Netherlands, showing that it is not just new mothers who could benefit from an omega-3 rich diet.

Fish containing high quantities of omega-3 polyunsaturated fatty acids (PUFAs) have previously been linked to a lower risk of post-natal depression in women, but there have been fewer studies on the general population.

Researchers from the Erasmus Medical Centre in Rotterdam compared 264 adults over 60 years old with depressive symptoms (including just over 100 with depressive disorders), to 461 randomly selected reference subjects. They used blood samples to measure concentrations of omega-3 and omega-6 fatty acids in the blood.

Subjects with depressive disorders had a higher ratio of omega-6 to omega-3 PUFAs, but differences in individual PUFAs were mostly small, report the researchers in this month's American Journal of Clinical Nutrition​. However, depressed subjects with normal C-reactive protein concentrations (a marker for atherosclerosis) had a substantially altered fatty acid composition. Omega-3 fatty acids were significantly lower, and ratios of omega-6 to omega-3s were higher, in subjects with depressive disorders than in control subjects. The normal C-reactive protein levels mean that the findings were not due to atherosclerosis, added the team.

It is thought that low levels of dietary omega-3 are associated with low levels of a brain chemical called serotonin, which contributes to depression. Oily fish such as salmon, tuna, sardines and herring are especially rich in omega-3.

The team concludes: " In community-dwelling persons, fatty acid composition is related to depression. Because this relation was not secondary to inflammation, atherosclerosis, or possible confounders, it suggests a direct effect of fatty acid composition on mood."​