Three more cases of Alzheimer’s disease will have been diagnosed by the time you finish reading this article. More than 5 million people have Alzheimer’s in the United States alone (44 million worldwide), and the rate of new diagnosis is about one patient every minute, with no cure on the horizon. Now a new study adds evidence to the argument that fish oil supplementation could be one of the best preventives we have against the disease--at least for people not at genetic risk of developing it.
Researchers from Rhode Island Hospital studied three groups of older adults, ages 55-90, using neuropsychological tests and brain magnetic resonance imaging (MRI) every six months. The group included 229 adults with no signs of the disease; 397 who were diagnosed with mild cognitive impairment; and 193 with Alzheimer’s. All participants were part of the Alzheimer’s Disease Neuroimaging Initiative (ADNI), which began in 2003 and ended in 2010.
Results showed that adults taking fish oil, who had not yet developed Alzheimer’s, experienced significantly less cognitive decline and brain shrinkage than adults not taking fish oil. Cognitive decline was measured using the Alzheimer's Disease Assessment Scale (ADAS-cog) and the Mini Mental State Exam (MMSE). (Unfortunately, the study did not specify the amount of fish oil taken, nor the percentage of EPA and DHA in the supplements.)
These are promising results, but they have one notable caveat: benefits of taking fish oil only held true for people lacking the main genetic risk factor for developing Alzheimer’s, known as APOE ε4 . The researchers think that people with APOE ε4 are incapable of metabolizing DHA, the fatty acid in fish oil thought to promote cognitive benefits.
The researchers add, however, that it’s still possible that starting fish oil supplementation during or before middle age could protect against developing Alzheimer’s even for people with the genetic marker. If you think of the gene for Alzheimer’s as a light switch, taking fish oil earlier in life could prevent the switch from being flicked on.
At least that’s the hope, and given the fact that Alzheimer’s—the sixth leading cause of death in the U.S.—still evades a cure, fish oil will continue to be a hot target of cognitive research as a possible shield against developing the disease.
The study was published in the journal Alzheimer's & Dementia.
You can find David DiSalvo on Twitter@neuronarrative and at Forbes. His latest book is Brain Changer: How Harnessing Your Brain’s Power To Adapt Can Change Your Life.