Low levels of the omega-3 fatty acid may contribute to the neurodegenerative disease
UC Irvine researchers have discovered that markedly depleted amounts of an omega-3 fatty acid in brain tissue samples from Alzheimer's patients may be due to the liver's inability to produce the complex fat, also contained in fish-oil supplements.
Low levels of docosahexaenoic acid, or DHA, have been associated with the chronic neurodegenerative disease affecting millions of Americans, but no cause had been identified.
In postmortem liver tissue from Alzheimer's patients, the UCI team found a defect in the organ's ability to make DHA from shorter molecules present in leafy plants and other foods. Previous studies have shown that most brain DHA is manufactured in the liver.
Non-Alzheimer's livers did not have this defect, said Daniele Piomelli, the Louise Turner Arnold Chair in the Neurosciences and director of the Center for Drug Discovery at UCI, who led the research with Giuseppe Astarita, project scientist in pharmacology.
"We all know Alzheimer's is a brain disease, but our findings - which were totally unexpected - show that a problem with liver fat metabolism can make people more vulnerable," Piomelli said. "They also suggest a reason why clinical trials in which Alzheimer's patients are given omega-3 fatty acids to improve cognitive skills have had mixed results."
The study appears Sept. 8 in the open-access, peer-reviewed journal PLoS ONE.