Listed in Issue 176


FOTUHI and COLLEAGUES, Center for Memory and Brain Health, LifeBridge Health Brain & Spine Institute, Sinai Hospital of Baltimore, Baltimore, MD 21209, USA. reviewed the literature to study the association between eating fish or taking omega-3 fatty acid supplements and the risk of cognitive decline or Alzheimer's disease.


Long-chain omega-3 fatty acids could have neuroprotective properties against dementia, which is becoming a major global public health issue.


We conducted a systematic review of the literature to establish the association between eating fish (a source of long-chain omega-3 fatty acids) or taking long-chain omega-3 fatty acid supplements and the risk of cognitive decline or Alzheimer disease (AD). We identified eleven observational studies and four clinical trials.


All three observational studies that used cognitive decline as an outcome reported significant benefits, whereas only four of eight observational studies that used incidence of AD or dementia as an outcome reported positive findings. None of four small clinical trials provided convincing evidence for the use of this approach in the prevention or treatment of any form of dementia. In summary, the existing data favour a role for long-chain omega-3 fatty acids in slowing cognitive decline in elderly individuals without dementia, but not for the prevention or treatment of dementia (including AD). This apparent dichotomy might reflect differences in study designs with regard to participants, dosages, the ratio of long-chain omega-3 to omega-6 fatty acids, or the choice of outcome measurements.


Large clinical trials of extended duration should help to provide definitive answers. [References: 77]


Fotuhi M, Mohassel P and Yaffe K. Fish consumption, long-chain omega-3 fatty acids and risk of cognitive decline or Alzheimer disease: a complex association. [Review] [77 refs]. Nature Clinical Practice Neurology. 5(3):140-52. Mar 2009.

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