Findings published in the journal Alzheimer's & Dementia indicated that fish oil supplements may conserve brain volume and cognition across the spectrum of normal aging and neurodegeneration.
“This study is the first to report an association between fish oil supplements use and brain structural changes in all three cognitive diagnostic groups; these findings may suggest a potential role for fish oil supplements by reducing neurodegeneration over time,” wrote the researchers. “The neuroprotective activities of n-3 PUFAs may be largely mediated through vascular effects; however, other mechanisms have been proposed, including the activities of neuroprotectin D1 (NPD1), a potent lipid mediator synthesized from DHA during periods of oxidative stress.”
The study analyzed data from 229 cognitively normal individuals, 397 patients with mild cognitive impairment, and 193 patients with Alzheimer's disease. While all the groups experienced benefits, the response was not observed for people with the genetic risk factor for Alzheimer's disease (AD) known as ApoE4. Previous data indicates that carriers of the APOE4 allelic variant (about 25% of whites) are at a several-fold increased risk of Alzheimer’s disease.
Causal?
However, the researchers could not conclude a causal effect of fish oil supplements on cognition and brain atrophy. Despite this, the results “highlight the need for future research on the effects of long-term fish oil supplement use on cognitive aging and dementia prevention in middle-aged and older adults”, they said.
Harry Rice, PhD, VP of regulatory and scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED), agreed with the investigators' conclusion that there is a need for future research on the effects of long-term n-3 LCPUFA use on cognitive aging and dementia prevention.
“What I think is the really important take-away is the need to screen subjects for APOE e4 carrier status,” he added. “People with the APOE e4 allele have an increased risk of developing Alzheimer's Disease. Studies on cognitive aging that don't screen subjects for APOE e4 are destined for failure.”
Study details
Led by Lori Daiello, PharmD, the researchers analyzed data from 819 people across the spectrum of normal aging and neurodegeneration from the Alzheimer's Disease Neuroimaging Initiative (ADNI), a large multi-center, NIH-funded study. Of these, 117 reported regular use of fish oil supplements at the start of the study and for the duration of study follow-up.
The researchers compared cognitive functioning and brain atrophy for patients who reported routinely using these supplements to those who were not using fish oil supplements.
Results indicated that, compared to non-users, use of fish oil supplements was associated with better cognitive functioning during the study. However, this association was significant only in those individuals who had a normal baseline cognitive function and in individuals who tested negative for APOE4.
In addition, Dr Daiello and her colleagues observed a clear association between fish oil supplements and brain volume, but this association was only significant for those who were APOE4 negative.
“In the imaging analyses for the entire study population, we found a significant positive association between fish oil supplement use and average brain volumes in two critical areas utilized in memory and thinking (cerebral cortex and hippocampus), as well as smaller brain ventricular volumes compared to non-users at any given time in the study,” said Dr Daiello. “In other words, fish oil use was associated with less brain shrinkage in patients taking these supplements during the ADNI study compared to those who didn't report using them.”
Source: Alzheimer's & Dementia
Published online ahead of print, doi: 10.1016/j.jalz.2014.02.005
“Association of fish oil supplement use with preservation of brain volume and cognitive function”
Authors: L.A. Daiello, A. Gongvatana, S. Dunsiger, R.A. Cohen, B.R. Ott, and the Alzheimer's Disease Neuroimaging Initiative.