Eat seafood meal once a week to stay sharp

The age-related memory loss and thinking problems of study-participants who reported eating seafood less than once a week declined more rapidly compared to those who ate at least one seafood meal per week.

"This study helps show that while cognitive abilities naturally decline as part of the normal ageing process, there is something that we can do to mitigate this process," said study senior author Martha Clare Morris from Rush University Medical Centre in Chicago, US.

The findings were published online in the journal Neurology.

The researchers followed 915 people with a mean age of 81.4 years for an average of five years. 

At study enrollment, none had signs of dementia.

During the course of the study, each person received annual, standardized testing for cognitive ability in five areas -- episodic memory, working memory, semantic memory, visuospatial ability and perceptual speed. 

The study group also completed annual food frequency questionnaires, allowing the researchers to compare participants' reported seafood intake with changes in their cognitive abilities as measured by the tests.

The questionnaires included four types of seafood: tuna sandwiches; fish sticks, fish cakes and fish sandwiches; fresh fish as a main dish; and shrimp, lobster and crab. 

The participants were divided into two groups: those who ate at least one of those seafood meals per week and those who ate less than one of those seafood meals per week.

People who ate more seafood had reduced rates of decline in the semantic memory, which is memory of verbal information. They also had slower rates of decline in a test of perceptual speed, or the ability to quickly compare letters, objects and patterns, the findings showed.

Seafood is the direct nutrient source of a type of omega-3 fatty acid (docosahexaenoic acid) that is the main structural component of the brain.