Older adults who ate seafood or other foods containing omega-3 fatty acids at least once a week saw a slower decline in age-related memory loss and cognitive issues than those who ate such foods less frequently, according to research results published by the journal Neurology.
“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,” says Martha Clare Morris, Sc.D., a Rush University Medical Center nutritional epidemiologist and senior author of the paper. Scientists from Wageningen University in the Netherlands also were part of the study.
The study included 915 people (mean age: 81.4 years) for an average of five years. At the beginning of the study, none of the older adults had signs of dementia. The participants were recruited from people already taking part in the Rush Memory and Aging Project, a study of residents of more than 40 retirement communities and senior public housing, plus older adults identified through church groups and social service agencies.
During each year of the research, each person was tested for cognitive ability in five areas: episodic memory, working memory, semantic memory, visuospatial ability and perceptual speed. Participants also described their eating habits in annual food frequency questionnaires.
The questionnaires asked about 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 a week and those who ate less than one of those seafood meals a week.
Participants in the higher seafood consumption group ate an average of two seafood meals a week. Those in the lower group ate an average of 0.5 seafood meals a week.
The researchers found associations between seafood consumption and two of the areas of cognitive ability that they tested. 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 study did not find a significant difference in the rate of decline in episodic memory (recollection of personal experiences), working memory (short-term memory used in mental function in the immediate present) or visuospatial ability (comprehension of relationships between objects).
The results were the same after researchers adjusted for other factors that could affect memory and thinking skills, such as education, physical activity, smoking and participating in mentally stimulating activities. The protective association of seafood was even stronger among people with a common genotype, APOE-ε4, that increases the risk of developing Alzheimer’s disease.