Altered DHA Omega-3 Status in Alzheimer’s Disease
Plasma and Brain Fatty Acid Profiles in Mild Cognitive Impairment and Alzheimer’s Disease
Research Center on Aging and Department of Medicine, Universite de Sherbrooke , Sherbrooke, Quebec, Canada
The present investigation compared the individual fatty acid levels in blood plasma and brain cortical regions from deceased subjects (normal controls, those with mild cognitive impairment, and patients with Alzheimer’s disease (AD)) who resided in the Chicago area. The lipid fractions were analyzed by combined thin-layer and gas-liquid chromatographic procedures. The DHA (docosahexaenoic acid) omega-3 concentrations in the blood plasma biomarker (phospholipid) as measured in those with mild cognitive impairment were not significantly different from the healthy controls. However , the DHA levels were significantly lower (by 49 %) in the AD patients relative to controls (average of 2.4 mg/dL versus 4.7 mg/dL). The brain analyses (on the membrane phospholipid as phosphatidlyserine) revealed the level of DHA to be significantly lower by 14 % and 12 % in the mid-frontal and superior temporal regions, respectively, in the AD subjects relative to controls.
The present study adds to the somewhat inconsistent literature on this topic wherein some studies have reported significantly lower DHA levels in AD patients when compared to healthy subjects while others have not. In this regard, it is anticipated that future studies will attempt to determine if the lower levels of DHA in AD patients (relative to controls) result from lower dietary intakes of DHA and/or altered metabolism of DHA (via altered biosynthesis of DHA from the precursor omega-3 fatty and/or altered metabolism of DHA).