Fatty Acid Profiles in Demented Patients: Identification of Hexacosanoic Acid (C26:0) as a Blood Lipid Biomarker of Dementia

Background: Several lipid metabolism alterations have been described in the brain and plasma of Alzheimer's disease (AD) patients, suggesting a relation between lipid metabolism alteration and dementia. Objective: We attempted to identify blood fatty acids as biomarkers of dementia. Methods: Fatty acid profiles were established using gas chromatography with or without mass spectrometry on matched plasma and red blood cells (RBCs) of demented patients diagnosed with AD, vascular dementia, or other dementia, and compared with a control group of elderly individuals. The severity of dementia was evaluated with the Mini-Mental State Examination test. Results: Fatty acid analysis showed significant variations of fatty acid levels in demented patients including AD patients. The highest plasma and RBC accumulation was found with hexacosanoic acid (C26:0). Our data also support that alterations of desaturase and elongase activities may contribute to cognitive dysfunction. Conclusion: The variations of fatty acid levels and the accumulation of C26: 0 in the plasma and RBCs highlight an alteration of fatty acid metabolism in demented patients and point toward possible peroxisomal dysfunction. It is suggested that C26: 0 may constitute a convenient blood biomarker of dementia that could be useful in routine medical practice.