Additionally, long-chain n-3 fatty acid intake did not correlate with the occurrence of brain infarcts or the presence of Lewy bodies, while higher intake of the short-chain plant-based n-3 fatty acid, linoleic acid, did correspond to a reduction in brain infarcts, which did not vary by APOE ε4 status. Intake of n-3 fatty acids via fish oil supplementation had no significant impact on any marker of neuropathology.
Dr Morris and her team concluded that the finding of “no deleterious correlations of mercury on the brain is supported by a number of case-control studies that found no difference between Alzheimer disease patients and controls in mercury concentrations in the brain, serum, or whole blood.”
The investigators acknowledged several limitations to the study, the most significant of which was the observational design that eliminated the opportunity to identify causality in the data, and the use of post-mortem measurements of mercury, which did not allow for analysis of the impact of fish consumption over time, although the same group had determined in a previous study of 915 MAP participants that cognitive decline was slowed by weekly seafood consumption over a mean of 4.9 years.9 Likewise, there were limitations to the subjective measurements of seafood intake given on many questionnaires, and the broader impact of quantities of fish/seafood consumption greater than once weekly were not assessed.
An accompanying editorial by Edeltraut Kroger, PhD and Robert Laforce Jr, MD, PhD of Universite Laval in Quebec City, Quebec, Canada supported the findings of the study, concluding that, “patients and their families may be hopeful that interventions such as seafood consumption may help reduce clinical manifestations of Alzheimer disease or dementia, and the report by Morris et al provides reassurance that seafood contamination with mercury is not related to increased brain pathology.”
- 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;315:489-497.
- Kroger E, Laforce R, Jr. Fish consumption, brain mercury, and neuropathology in patients with Alzheimer disease and dementia. JAMA 2016;315:465-466.