JAMA: Association of seafood consumption, brain mercury level and APOEɛ4 status with brain neuropathology in older adults
A team of scientists in the US has found a link between seafood consumption and lower levels of Alzheimer’s-related features in the brains of people carrying a genetic risk factor of the disease. The research was published in the journal JAMA on 2 February 2016.
The study involved 286 people in their late 80s, who had previously completed a questionnaire about diet, particularly focusing on seafood consumption per week. The research team used this information to calculate dietary intake of omega-3 fatty acids, found in seafood, taking into account any use of dietary fish oil supplements. The volunteers generously donated their brains for research.
The research team looked for hallmark features of Alzheimer’s – amyloid and tau – in the brain. They found that overall, there was no association between the amount of seafood the volunteers consumed and the levels of amyloid and tau. However, when they focused on the 65 people who carried the APOEɛ4 gene (a gene that increases the risk of Alzheimer’s three-fold), they found that those who ate at least one piece of seafood a week had lower levels of amyloid in the brain. There was no association between seafood consumption and key features of dementia with Lewy bodies in the brain samples. The team also explored the link between diet and blood vessel changes in the brain. They found that higher levels of a particular type of fatty acid, alpha-linolenic acid, were associated with lower levels of vascular damage, even in people without the APOEɛ4 gene.
As well as studying key features of neurodegenerative disease in the brain, the researchers looked at mercury. Mercury is a toxin that can be found in seafood. They found that although there were higher levels of mercury in the brains of people who reported eating more seafood, there was no relationship between mercury and the hallmark features of Alzheimer’s disease. Higher mercury levels were associated with lower levels of vascular damage.
Dr Laura Phipps at Alzheimer’s Research UK, said:
“The omega-3 fatty acids found in oily fish are an important part of a balanced diet, and previous studies suggest they could play an important role in keeping the brain healthy. This study links moderate seafood consumption with lower levels of Alzheimer’s-related brain changes in elderly people who carry a risk gene for the disease, but we must be careful when drawing conclusions about the wider population. Current research is underway to investigate the benefits of a diet rich in omega-3 fatty acids in those at risk of memory and thinking problems, but at this time there is no evidence to suggest fish oil supplements could prevent dementia. While higher seafood consumption is linked to greater levels of mercury in the brain, it is encouraging to see that this did not appear to be associated with Alzheimer’s changes in the brain in this study.
“Dementia risk is a complex mix of age, genetics and lifestyle factors. The best current evidence suggests that what’s good for your heart is good for your head and that getting plenty of exercise, eating a healthy balanced diet, not smoking and keeping blood pressure and cholesterol in check could help reduce dementia risk.”