Seafood May Slow Down Cognitive Decline in Dementia Patients

“While higher seafood consumption is linked to greater levels of mercury in the brain, it is encouraging to see that this did not appear to be associated with Alzheimer’s changes in the brain in this study”.

Since diet is the most practical of all health strategies, Dr. Martha Clare Morris and her Rush Medical School colleagues chose to explore whether eating seafood might prevent dementia. “This may give us some clue as to why eating seafood could benefit some people over others – but we need further work to find out if this is the case”.

“The evidence is quite clear that people who consume healthier forms of fish [which are baked or broiled rather than fried] are going to end up with healthier brains”, said James T. Becker, professor of psychiatry and associate director of the Alzheimer’s Disease Research Center at the University of Pittsburgh, who was not involved in the current study. These elderly people were part of a research project on memory and ageing.

Participants in the study began reporting their food intake via questionnaire on average almost five years before their death.

The study findings were derived from 286 postmortem brain autopsies performed on a cohort of individuals initially free of dementia that the researchers followed for an average of 4.5 years until their death. Although the researchers found out that those who consumed more seafood had higher brain mercury levels, there is no reason to believe that it has any significant connection to the development of Alzheimer’s disease.

This study could not rule on whether people who regularly select seafood that tends to be higher in mercury, such as tuna and swordfish, have problems associated with the higher mercury exposure. After adjusting for age, sex, education, and total energy intake, seafood consumption was significantly correlated with decreased risk of neuropathologically defined Alzheimer disease among APOE ε4 carriers (β -0.53 score units; 95%CI -0.96 to -0.10). But they were also puzzled that fish oil supplements, which are also rich in omega 3, did not trigger a similar effect. On the other hand (or fin), seafood also is a source of the element mercury, which has been thought to cause damage to cells in the brain, contributing to cognitive impairment.

Researchers said their experiment is the first to examine the relationship between brain health and levels of mercury.

“It is to this day not quite clear whether the reason for the benefit of fish is to be found in its n-3 unsaturated fatty acid content, or whether the benefit from fish-containing diets is more complicated to understand”, she added. There was a correlation for higher intake levels of α-linolenic acid with lower odds of cerebral macroinfarctions.

The team, whose work is published in the JAMA medical journal, suspect that the omega-3 fatty acids in seafood may be responsible.

They said the mercury toxicity may have been reduced by selenium, a nutrient present in seafood.