CHICAGO—People who eat baked or broiled fish on a weekly basis may be improving their brain health and reducing their risk of developing mild cognitive impairment (MCI) and Alzheimer's disease, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA).

Cyrus Raji, M.D., Ph.D.

"This is the first study to establish a direct relationship between fish consumption, brain structure and Alzheimer's risk," said Cyrus Raji, M.D., Ph.D., from the University of Pittsburgh Medical Center and the University of Pittsburgh School of Medicine. "The results showed that people who consumed baked or broiled fish at least one time per week had better preservation of gray matter volume on MRI in brain areas at risk for Alzheimer's disease."

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.

For the study, 260 cognitively normal individuals were selected from the Cardiovascular Health Study. Information on fish consumption was gathered using the National Cancer Institute Food Frequency Questionnaire. There were 163 patients who consumed fish on a weekly basis, and the majority ate fish one to four times per week. Each patient underwent 3-D volumetric MRI of the brain. Voxel-based morphometry, a brain mapping technique that measures gray matter volume, was used to model the relationship between weekly fish consumption at baseline and brain structure 10 years later. The data were then analyzed to determine if gray matter volume preservation associated with fish consumption reduced risk for Alzheimer's disease. The study controlled for age, gender, education, race, obesity, physical activity, and the presence or absence of apolipoprotein E4 (ApoE4), a gene that increases the risk of developing Alzheimer's.

Gray matter volume is crucial to brain health. When it remains higher, brain health is being maintained. Decreases in gray matter volume indicate that brain cells are shrinking.

The findings showed that consumption of baked or broiled fish on a weekly basis was positively associated with gray matter volumes in several areas of the brain. Greater hippocampal, posterior cingulate and orbital frontal cortex volumes in relation to fish consumption reduced the risk for five-year decline to MCI or Alzheimer's by almost five-fold.

"Consuming baked or broiled fish promotes stronger neurons in the brain's gray matter by making them larger and healthier," Dr. Raji said. "This simple lifestyle choice increases the brain's resistance to Alzheimer's disease and lowers risk for the disorder."

The results also demonstrated increased levels of cognition in people who ate baked or broiled fish.

"Working memory, which allows people to focus on tasks and commit information to short-term memory, is one of the most important cognitive domains," Dr. Raji said. "Working memory is destroyed by Alzheimer's disease. We found higher levels of working memory in people who ate baked or broiled fish on a weekly basis, even when accounting for other factors, such as education, age, gender and physical activity."

Eating fried fish, on the other hand, was not shown to increase brain volume or protect against cognitive decline.

Coauthors are Kirk Erickson, Ph.D., Oscar Lopez, M.D., Lewis Kuller, M.D., H. Michael Gach, Ph.D., Paul Thompson, Ph.D., Mario Riverol, M.D., Ph.D., and James Becker, Ph.D.

Video clips

• Video clip (2,010 KB)
   This video highlights the positive effects of fish consumption on brain structure in both the right and left hemispheres, particularly in the frontal lobes.
• Video clip (103 KB)
   Images of the brain.
• Video clip (129 KB)
   Images of the brain.

Images

Figure 1: This image shows a cutaway side view of the left side of the brain illustrating in red, green and yellow colors the beneficial effects of weekly fish consumption on gray matter volume. Hotter colors denote a stronger effect. Consuming fish on a weekly basis is linked to increased gray matter volume in the frontal cortex, posterior cingulate gyrus and temporal cortex on the left side of the brain.	Figure 2: This image shows a cutaway side view of the right side of the brain illustrating in red, green and yellow colors the beneficial effects of weekly fish consumption on gray matter volume. Hotter colors denote a stronger effect. As was seen with the left side of the brain, consuming fish on a weekly basis is linked to increased gray matter volume in the frontal cortex, posterior cingulate gyrus and temporal cortex on the right side of the brain.	Figure 3: This image shows sagittal, coronal and axial views of the main effect of fish consumption on the brain. Higher hippocampal volume with fish consumption is seen at the intersection of the crosshairs in the right hippocampus. Hotter colors denote a stronger effect.	Figure 4: This image shows a cutaway side view of the left side of the brain illustrating in red and yellow colors areas of the brain that are protected from shrinkage due to small vessel ischemic disease in weekly fish consumers. People who consume fish on a weekly basis show a sparing of gray matter atrophy from ischemic disease in the frontal cortex, precuneus and occipital cortex on the left side of the brain.
Figure 5: This image shows a cutaway side view of the right side of the brain illustrating in red and yellow colors areas of the brain that are protected from shrinkage due to small vessel ischemic disease in weekly fish consumers. People who consume fish on a weekly basis show a sparing of gray matter atrophy from ischemic disease in the frontal and occipital cortex on the right side of the brain.