Written by Greg Arnold, DC, CSCS. Alzheimer’s patients with DHA red blood cell levels less than 3.9% “performed more poorly on tests of visual memory, executive function, and abstract thinking” compared to patients with levels more than 3.9%.
Alzheimer’s disease risk doubles every 5 years after the age of 65, with as many as half of people over the age of 85 exhibiting signs of the disease. Up to 5.3 million Americans currently have Alzheimer’s disease, but that is expected to double by 2050 due to the aging of the population. It’s the sixth leading cause of death and is the fifth leading cause among persons age 65 and older in the U.S. (1).
Now a new study (2) suggests that omega-3 fat levels in red blood cells may affect brain circulation and be an early marker of Alzheimer’s disease risk. In the study, researchers analyzed the blood samples of 1,575 patients (721 men, 854 women) aged 58 to 76 participating in the Framingham Study and not showing clinical signs of dementia. Specifically, they looked at the red blood cell levels of an omega-3 fat called DHA (which is found in highest levels in the brain) and its correlation to performance on cognitive tests and brain MRI to measure brain volume. The researchers looked specifically at DHA levels in red blood cells because it specifically measures dietary fat intake for the past 4 months (the lifespan of a red blood cell) while levels taken outside of the red blood cell (in what’s called plasma) only reflect fat intake from the last few days. (3)
In examining the results, the researchers found a specific threshold of DHA levels in red blood cells that elicited significant differences in a type of brain tissue called “white matter” where nerves in the brain are located (4). Specifically, those with more than 3.9% of DHA levels in red blood cells had “significantly higher” white matter compared to those with less than 3.9% of DHA levels in red blood cells, with decreased white matter being a sign of altered brain circulation. When they applied the threshold to the cognitive tests, those with DHA red blood cell levels less than 3.9% “performed more poorly on tests of visual memory, executive function, and abstract thinking” compared to patients with levels more than 3.9%.
Unfortunately, the researchers did not make any recommendations of DHA intake that could bring people above this 3.9% red blood cell threshold nor did they assign any risk reductions to Alzheimer’s disease with this threshold. They went on to conclude that “lower red blood cell DHA levels are associated with smaller brain volumes and a “vascular” pattern of cognitive impairment even in persons free of clinical dementia.”
Source: Tan, Z. S., W. S. Harris, A. S. Beiser, R. Au, J. J. Himali, S. Debette, A. Pikula et al. “Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging.” Neurology 78, no. 9 (2012): 658-664.
Copyright © 2012 by AAN Enterprises, Inc.
Posted March 16, 2012.
References:
- “Demential/Alzheimer’s Disease” – from the Centers for Disease Control and Prevention website.
- Tan ZS. Neurology® 2012;78:658–664
- Arab L. Biomarkers of fat and fatty acid intake. J Nutr 2003;133(suppl 3):925S–932S. “White Matter of the Brain – Overview” – from the University of Maryland Medical Center website.
