RD&T contributor, Dr. Joel Furhman, discusses the potential benefits of DHA in protecting against dementia and Parkinson’s in this article. In particular, he addresses the importance of the conservative use of supplements as found through his decades of experience in primary care practice.
DHA and Dementia
As of 2009, there were at least a dozen epidemiological studies that associate reduced blood levels of omega-3 fatty acids or omega-3 or fish intake with increased risk for age-related cognitive decline or dementia.34 In 2015, a dose-response meta-analysis of dietary DHA found that a 0.1 g/day increase in DHA intake was associated with a 14 percent lower risk of dementia and a 37 percent lower risk of Alzheimer’s Disease.35 DHA is broadly neuroprotective via multiple mechanisms, including limiting the production and accumulation of amyloid beta-peptide toxin that is widely believed to drive the disease.12,36
Importance of early prevention
That does not mean that giving a DHA supplement to someone with established cognitive impairment or to the elderly after a lifetime of deficiency will prevent or reverse established brain shrinkage or memory loss. Studies show that giving supplements to those who already have memory loss or dementia does not work.37 This reinforces how important early prevention is and the lack of effectiveness of supplementing after brain shrinkage has occurred should not be used to confuse people into thinking that DHA adequacy is not important.
For example, in the Framingham Heart Study, the top quartile of plasma DHA level was associated with a significant 47 percent reduction in the risk of developing all-cause dementia.38 This epidemiologic study was further confirmed with a case-controlled cohort study called the Rancho Bernardo Study that tracked dietary DHA and plasma DHA to confirm consistency and they found dietary DHA in the highest third was associated with a 73 percent reduced odds of all-cause dementia and plasma DHA in the highest third had a 65 percent reduced odds of all-cause dementia.39
