Regular fish consumption may reduce risk of Alzheimer’s disease

People who eat fish on a weekly basis may be both improving their brain health and reducing their risk of developing mild cognitive impairment and Alzheimer's disease, according to a new US study.

In the observational study, information on fish consumption was gathered from 260 cognitively normal individuals using a food frequency questionnaire (1). Of all the participants, 163 ate fish on a weekly basis; the majority of whom enjoyed fish from one to four times a week. Each of them underwent a volumetric magnetic resonance imaging (MRI) of the brain, including a brain mapping technique that measures gray matter volumes, so that the relationship between weekly fish consumption and brain structure at the beginning of the study and 10 years later could be measured. The data were then analyzed to determine whether the gray matter volume preservation associated with fish consumption reduced the risk of Alzheimer's disease. The study results showed that consumption of baked or broiled fish on a weekly basis was associated with bigger gray matter volumes in several areas of the brain, which reduced the risk of developing mild cognitive impairment (MCI) or Alzheimer's disease by almost fivefold. In addition, participants who regularly ate fish had higher levels of working memory, allowing them to focus on tasks and commit information to short-term memory – one of the most important cognitive domains. Eating fried fish, on the other hand, was not shown to increase brain volume or protect against cognitive decline.

The researchers concluded that people who consume baked or broiled fish at least one time per week may have a better preservation of gray matter volume in areas at risk for Alzheimer's disease. The omega-3 fatty acids in fish may promote stronger neurons in the brain's gray matter by making them larger and healthier, thereby increasing the brain's resistance to Alzheimer's disease and lowering the risk of the disorder.

Alzheimer's disease is an incurable, progressive brain disease that slowly destroys memory and cognitive skills. According to the National Institute on Aging, as many as 5.1 million Americans may have Alzheimer's disease. In MCI, memory loss is present, but to a lesser extent than in Alzheimer's disease. People with MCI often go on to develop Alzheimer's disease. Gray matter volume is crucial to brain health. When it stays high, brain health is being maintained. Decreases in gray matter volume indicate that brain cells are shrinking.

1. Raji C. et al. Regular fish consumption is associated with larger gray matter volumes and reduced risk for cognitive decline in the cardiovascular health study. Radiological Society of North America annual meeting 2011.