In the decades ahead, public health officials predict growing numbers of Alzheimer's disease and dementia patients. While scientists labor in their labs trying to create new treatments, older adults wonder whether there may be some practical step they can take to prevent their own decline. A new study addresses this everyday need.

Rush University researchers find older adults who ate the most seafood had less Alzheimer’s-related damage in their brains compared to those who ate little or no seafood. Yet, fish oil supplements did not appear to offer similar benefits.

Eat Your Way To A Better Brain

The Mediterranean diet, which is rich in fruit, vegetables, olive oil, and fish, appears to decrease the risk of Alzheimer's disease, explain the authors of an accompanying editorial. Fatty fish and fish oils have also been associated with cognitive benefits, including a slowing of cognitive decline in older adults. Since diet is the most practical of all health strategies, Dr. Martha Clare Morris and her Rush Medical School colleagues decided to explore whether eating seafood might prevent dementia.

The research team turned to the Memory and Aging Project (MAP), which included residents in Chicago retirement communities. The researchers focused on those MAP participants who died between 2004 and 2013 and had a brain autopsy performed. The average age of the participants at death was 89.9, while 67 percent were women. Importantly, all of the selected participants had completed a dietary assessment, allowing the researchers to compare each participant’s autopsy results with their favorite foods.

The researchers discovered those who said they ate seafood one or more times a week had less plaques or neurofibrillary tangles, the signature signs of Alzheimer's disease, than those who ate little or no fish. Although eating seafood meant higher levels of mercury in these participants’ brains, the researchers said this did not equate to increased brain pathology.

Eating lots of seafood even helped people with the APOE genetic variation — this is linked to an increased risk of developing Alzheimer’s. Among participants carrying the faulty gene, disease was less common among the frequent seafood eaters compared to those who disliked fish.

To reach the beneficial level, the researchers say you would need to eat more than two seafood meals per week. That said, the team was not able to identify specific types of seafood as "best" for protection.

Finally, the team says taking fish oil supplements did not show similar effects. While it may be tempting to suggest the whole fish is needed to gain a benefit, the real issue is inconsistency. The few participants who used supplements did not take them with any regularity.

Source: Morris MC, Brockman J, Schneider JA, et al. Association of Seafood Consumption, Brain Mercury Level, and APOE ε4 Status With Brain Neuropathology in Older Adults. JAMA. 2016.

Kroger E, Laforce Jr. R. Fish Consumption, Brain Mercury, and Neuropathology in Patients With Alzheimer Disease and Dementia. JAMA. 2016.