New research has shown that eating seafood and other omega-3 rich foods at least once a week can help protect against cognitive decline in seniors.

Although previous studies have shown the benefits of eating seafood, including fish, and omega-3 fatty acids to reduce cognitive decline, few studies have looked at a link between omega-3 consumption and specific types of cognitive ability.

In this new study the team of researchers from Rush University Medical Center, USA, and Wageningen University in the Netherlands followed 915 people, none of whom had dementia at the beginning of the study, for an average of five years. The mean age of participants was 81.4 years.

During the study participants underwent an annual, standardized test for cognitive ability in five different areas.

Participants also completed annual food questionnaires which assessed their reported seafood intake, and included tuna sandwiches; fish sticks, fish cakes and fish sandwiches; fresh fish as a main dish; and shrimp, lobster and crab.

The participants were then divided into two groups: those who ate at least one of these seafood meals per week and those who ate less than one of these seafood meals per week, with seafood intake compared against any changes seen in participant's cognitive abilities, as measured by the tests.

After taking into account various factors that could also affect memory and thinking skills, such as education, physical activity, and smoking, the results showed that the participants who ate seafood at least once a week showed a slower decline in semantic memory (memory of verbal information) and perceptual speed (the ability to quickly compare letters, objects and patterns) than those who ate seafood less than once a week.

However the study didn't find a significant difference in the rate of decline in the three other areas of memory tested: episodic memory (remembering personal experiences), working memory (the short-term memory used in the immediate present) and visuospatial ability (the ability to understand the relationships between objects).

The study also found that seafood had a protective effect among participants with the genotype that increases the risk of developing Alzheimer's disease.

Commenting on the results Martha Clare Morris, senior author of the paper said, "This study helps show that while cognitive abilities naturally decline as part of the normal aging process, there is something that we can do to mitigate this process."

The findings were published in Neurology, the medical journal of the American Academy of Neurology.