More than a dozen epidemiological studies have reported that reduced levels or intake of omega-3 fatty acids or fish consumption is associated with increased risk for age-related cognitive decline or dementia such as Alzheimer's disease (AD).
Increased dietary consumption or blood levels of docosahexaenoic acid (DHA) appear protective for Alzheimer's disease and other dementia in multiple epidemiological studies; however, three studies suggest that the ApoE4 genotype limits protection.
DHA is broadly neuroprotective via multiple mechanisms that include:
• Neuroprotective DHA metabolites,
• Reduced arachidonic acid metabolites,
• And increased trophic factors or downstream trophic signal transduction.
DHA is also protective against several risk factors for dementia including:
• Head trauma,
• And cardiovascular disease.
DHA is specifically protective against Alzheimer’s disease via additional mechanisms:
• It limits the production and accumulation of the amyloid beta peptide toxin that is widely believed to drive the disease;
• And it also suppresses several signal transduction pathways induced by Abeta, including two major kinases that phosphorylate the microtubule-associated protein tau and promote neurofibrillary tangle pathology.
Based on the epidemiological and basic research data, expert panels have recommended the need for clinical trials with omega-3 fatty acids, notably DHA, for the prevention or treatment of age-related cognitive decline - with a focus on the most prevalent cause, Alzheimer’s disease.
Clinical trials are under way to prevent and treat Alzheimer’s disease. Results to date suggest that DHA may be more effective if:
• It is begun early
• Or used in conjunction with antioxidants.
Source: Prostaglandins, Leukotrieines, and Essential Fatty Acids, Jun 10, 2009. PMID: 19523795, by Cole GM, Ma OL, Frautschy SA. Department of Medicine and Department of Neurology at University of California, Los Angeles; GRECC Veterans Affairs, Greater Los Angeles Healthcare System, North Hills, California, USA. [E-mail: firstname.lastname@example.org]