Omega-3 fatty acids might reduce cognitive decline risk

Key takeaways:

• Supplementation or dietary intake of omega-3 fatty acid may reduce the risk for cognitive decline.
• Long-term users of omega-3 fatty acid supplements had a 64% reduced risk for Alzheimer’s disease.

Omega-3 fatty acid may reduce the risk for cognitive decline and could be particularly helpful for populations at high genetic risk for Alzheimer’s disease, according to researchers.

Previous data have linked omega-3 fatty acids to a lower dementia risk, sparking a rising interest in how they may play a role in dementia prevention, Wei Xu, MD, PhD, of the neurology department at Qingdao Municipal Hospital Group in China and associate editor of the Journal of Alzheimer’s Disease, and colleagues wrote.

Omega-3 fatty acids — a heterogeneous group of fatty acids with a double bond at the 3 carbon atom, mainly including -linolenic acid, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) — are nootropic agents that are good for cognitive preservation, anti-inflammation and brain development, according to the researchers. People primarily obtain omega-3 fatty acids through dietary intake, especially by eating fish.

Given that patients with Alzheimer’s disease tend to have lower concentrations of omega-3 fatty acids compared with cognitively healthy individuals, Xu told Healio that taking regular supplements or undergoing omega-3-oriented dietary interventions “could be promising approaches to lowering dementia risk, especially for those at high genetic risk.” So, Xu and colleagues conducted a study to better understand the longitudinal relationships of omega-3 polyunsaturated fatty acids intake as well as blood biomarkers with the risk for cognitive decline, dementia or Alzheimer’s disease during a 6-year follow-up.

“Given the lack of effective therapeutic strategy and the high disease burden, it is imperative to identify modifiable risk factors to prevent or postpone the onset of Alzheimer’s Disease,” Xu and colleagues wrote in the American Journal of Clinical Nutrition.

The researchers evaluated data from 1,135 participants with a mean age of 73 years who did not have dementia in the Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort. Then they conducted causal dose-response analyses and a meta-analysis on 48 longitudinal studies involving 103,651 participants.

Xu and colleagues found that long-term supplementation or dietary intake of omega-3 fatty acid might reduce the risk for cognitive decline or Alzheimer’s disease.

In the ADNI cohort studied, those who were long-term users of omega-3 fatty acid supplements showed a 64% reduced risk for Alzheimer’s disease (adjusted HR = 0.36; 95% CI, 0.54-0.96).

After they incorporated the 48 studies, the researchers wrote that moderate-to-high level evidence indicated that dietary omega-3 fatty acid intake could reduce the risk for cognitive decline or all-cause dementia by about 20%, particularly for DHA intake (RR = 0.82).

Additionally, each increment of 0.1 g per day of DHA or EPA intake was linked to between an 8% and 9.9% lower risk for cognitive decline.

“In the present study, we found that supplemental omega-3 fatty acid use was significantly associated with a lower risk of AD,” Xu said. “Our meta-analysis findings strengthened the association of dietary omega-3 fatty acid intake and its peripheral biomarkers with risk of Alzheimer’s disease, dementia or cognitive decline.”

He added that the findings have important clinical implications.

“First, our findings provide convincing epidemiological support for adherence to omega-3 supplementation and omega-3 oriented dietary intervention to prevent dementia,” Xu said. “Second, for populations at high genetic risk for Alzheimer’s disease, the adverse effects of genetic risk factors can be attenuated and even neutralized by long-term omega-3 supplementation. Third, peripheral markers of omega-3 may serve as predictors of cognitive decline or dementia.”