Researchers at the University of Southern California (USC) have conducted a small clinical trial which has revealed important clues about Omega-3s role in averting or curtailing cognitive decline in human brain.
This is the first Alzheimer’s prevention study to compare levels of omega-3s in the blood with those in the central nervous system.
The findings, “Brain delivery of supplemental docosahexaenoic acid (DHA): A randomized placebo-controlled clinical trial” have been published in EBioMedicine.
The study suggests that higher doses of omega-3 supplements may be needed to make a difference, because dramatic increases in blood levels of omega-3s are accompanied by far smaller increases within the brain.
“Trials have been built on the assumption that omega-3s get into the brain,” notes senior author Hussein Yassine, MD, associate professor of medicine and neurology at the Keck School of Medicine of USC. “Our study was specifically designed to address this question.”
The researchers recruited 33 participants who had risk factors for Alzheimer’s but were not cognitively impaired. All participants had a family history of the disease, a sedentary lifestyle, and a diet low in fatty fish. Fifteen carried a gene variant called APOE4, which is linked to inflammation in the brain and increases Alzheimer’s risk by a factor of four or more; the other 18 were noncarriers.
Yassine and his colleagues gathered samples of blood plasma and cerebrospinal fluid from participants at the outset, and again at the end of the study period. The scientists looked at levels of two omega-3 fatty acids: DHA and eicosapentaenoic acid (EPA), a potent anti-inflammatory that the body derives from a small portion of its DHA intake.
The researchers found that at the end of the six months, participants who took omega-3 supplements had 200 percent more DHA in their blood compared to those who took placebos. In contrast, the DHA found in cerebrospinal fluid was only 28 percent higher in the treatment group than the control group. This result hints that measuring omega-3 levels in the blood may not indicate how much is reaching the brain.