Omega-3 fatty acids are essential for human health. They participate in pathways involved in the biosynthesis of hormones that regulate blood clotting, contraction and relaxation of artery walls, and inflammation. They have been shown to help prevent heart disease and stroke; may help control lupus, eczema, and rheumatoid arthritis; and may play protective roles in cancer and other conditions. Findings from a new study suggest that omega-3 fatty acids slow cognitive decline in Alzheimer’s disease.

Alzheimer’s disease is a neurodegenerative disorder characterized by progressive memory loss and cognitive decline. The primary risk factor for Alzheimer’s disease is aging, with risk roughly doubling every five years after the age of 65 years. Nutritional status also plays key roles in Alzheimer’s disease risk and pathology. The intervention study involved 33 people who had been diagnosed with Alzheimer’s disease. Approximately half of the participants took a supplement providing 2.3 grams of omega-3 fatty acids daily for six months; the other half took a placebo. All participants took the Mini Mental State Examination (MMSE), a widely accepted measure of memory and cognitive function, before and after the intervention. The study investigators collected cerebrospinal fluid samples before and after the intervention to measure several biomarkers associated with neurodegenerative diseases and inflammation, including amyloid beta proteins, tau, interleukin 6, chitinase-3-like protein 1 (YKL-40), and neurofilament light (NfL). YKL-40 is associated with neuroinflammation, and NfL is associated with damage to the axons of nerves in brain white matter.

The MMSE scores of the participants who took the omega-3 fatty acid supplements remained stable over the six-month intervention, decreasing by only 0.06 points, but the scores of those who took the placebo decreased by two points. The two groups' biomarkers were similar at the beginning of the intervention, but YKL-40 and NfL increased slightly in the group that received the omega-3 fatty acid supplement, indicating a possible increase in neurodegeneration and inflammatory responses. However, the increase in the two biomarkers did not correlate with the participants' MMSE scores.

These findings suggest that omega-3 fatty acids help maintain memory and cognitive function in older adults with Alzheimer’s disease. This was a very small study, however, and further research is needed to confirm any protective effects of omega-3 fatty acid intake in Alzheimer’s disease.

• Link to study abstract.

• Learn more about the links between DHA (a type of omega-3 fatty acid) and Alzheimer’s disease in this article by Dr. Rhonda Patrick.