A decline in DHA levels has been observed in Alzheimer’s patients in areas of the brain associated with cognition and memory, namely the hippocampus and frontal cortex. A diet rich in omega-3s (rich in DHA; fish oils) could therefore be beneficial in restoring cognitive performance and brain function. Animal studies have shown that omega-3 supplementation can lower total beta-amyloid levels in the brain. Furthermore, some studies have shown an improvement in cognition after omega-3 supplementation compared to those without. However, the majority of these studies investigated long-term omega-3 supplementation over a prolonged period (>10 years). Therefore, long-term supplementation prior to advanced-disease stage progression is essential.
As to their role in the treatment of Alzheimer’s disease, there is no significant evidence in this area, especially when the disease has progressed to a moderate to severe stage. However, some studies suggest a weak beneficial effect, namely, a mild slowing down of the onset of Alzheimer’s disease if omega-3 is taken when symptoms are only mild. As with any observational study looking at the effects of natural or herbal supplements in the treatment or prevention of disease, more randomized controlled studies are essential, with sufficiently large sample sizes.