The American Psychiatric Association has called attention to two very recently published articles that extend the growing literature on the benefits of omega-3 fatty acids. One article, to be published in the prestigious journal Neurology (presently on-line), is a well-controlled comparison of various nutritional supplements as protection against the accumulation of dementia-associated complex proteins. Another, just published online May 17 ahead of print publication in the Annals of Neurology, revealed that a diet higher in saturated fatty acids was associated with faster cognitive decline in over 6,000 participants in the Women’s Health Study.
NOTE: Please see my blog post February 28, 2012 for a primer on Essential Fatty Acids: MAKING SENSE OF OMEGA-3 FATTY ACIDS: The Skinny on Fish Oils and Brain Health.
The Annals of Neurology article, Dietary fat types and 4-year cognitive change in community-dwelling older women, by Olereke, et al, makes a strong case that “higher mono-unsaturated fatty acid (MUFA) intake was related to better [cognitive health] trajectories. Thus, different consumption levels of the major specific fat types, rather than total fat intake itself, appeared to influence cognitive aging.” 6,183 older “community based” women were followed for 4+ years. These women, who were all age 45 and older, participated in testing every two years, and also completed food questionnaires at the start of the study. The investigators “found over time, women who ate the highest amounts of saturated fat had the worst overall brain function and memory, compared to the women who at the least.”
The Neurology article entitled , “Nutrient Intake and Plasma Beta-Amyloid” by Gu et al, indicates that people who eat a diet rich in fish oils may significantly lower the risk of developing memory problems and Alzheimer’s disease. 1200 dementia-free subjects over the age of 65 were studied with blood testing and detailed review of dietary patterns. The associations of two types of plasma β-Amyloids and dietary intake of 10 nutrients were examined using linear regression models, adjusted for age, gender, ethnicity, education, caloric intake, apolipoprotein E genotype, and recruitment wave. Nutrients examined included saturated fatty acid, monounsaturated fatty acid, omega-3 polyunsaturated fatty acid (PUFA) [fish oils–see note below], omega-6 PUFA, vitamin E, vitamin C, β-carotene, vitamin B12, folate, and vitamin D. Only the fish oils were associated with reduction of β-Amyloids.
Although β-Amyloids in blood plasma could possibly not reflect the amyloid protein levels in the brain, it is known that brain amyloid load correlates with dementing conditions. It is generally believed that amyloid accumulation is toxic to neurons, but there are some research lines suggesting that brain amyloid accumulation is the result of dementing processes and not its cause. In any event, the authors conclude:
“Our data suggest that higher dietary intake of ω-3 PUFA is associated with lower plasma levels of Aβ42, a profile linked with reduced risk of incident Alzheimer’s Disease and slower cognitive decline in our cohort.”
Two other studies reported in April have remarkably congruent findings. From April 10 in the daily APA bulletin: Health Day reported, “Omega-3 fatty acids from fish may help prevent age-related cognitive decline, according to two new studies.” The studies were both published in April’s American Journal of Clinical Nutrition. “In one study, Dutch researchers examined the diet and cognitive function of 210 men, ages 70 to 89. … The researchers concluded that consumption of approximately 400 milligrams of omega-3 fatty acids per day…protects against cognitive decline. In the other study, American researchers looked at omega-3 consumption and cognitive decline in 2,251 white males, ages 50 to 65.” While this “study found no association between baseline levels of omega-3 fatty acids in the men and overall cognitive decline…an analysis of specific types of cognitive decline did find that higher levels of omega-3 fatty acids were associated with protection against loss of verbal fluency.” Authors of both studies “recommended that clinical trials be conducted to determine the effect of dietary fish, fish oil or both in elderly people at risk of cognitive decline and Alzheimer’s disease.”