Giving long-term high doses of omega-3 DHA to carriers of the apolipoprotein E ε4 (APOE4) allele before the onset of Alzheimer’s disease (AD) dementia may reduce the risk for AD, or delay the onset of symptoms, and should be studied, according to an expert review published in JAMA Neurology. “Given the safety profile, availability, and affordability of DHA, refining an interventional prevention study in APOE4 carriers is warranted,” researchers noted..
In the earliest pre-dementia phase of the disease (stage I), participants would have evidence of brain imaging changes in areas vulnerable to AD. However, no cognitive changes, or only subtle ones, would be detectable. “In this stage, brain DHA metabolism is altered by APOE4, and brain imaging or CSF biomarkers can be used to select at-risk individuals and monitor the efficacy of supplementation,” they explained. It is for patients in an early prodromal stage of disease (stage II) that long-term high dose DHA supplementation could slow cognitive decline, the researchers stated. Patients in this group would have evidence of memory and/or executive decline but no significant impairment in activities of daily living. Stage III would represent clinical AD with impairments in multiple cognitive domains. DHA supplementation would probably not be beneficial in this group.