Cognitive efficacy of omega‑3 fatty acids in Alzheimer's disease: A systematic review and meta‑analysis

Alzheimer's disease (AD), the most prevalent form of dementia, is a progressive neurodegenerative disorder characterized by a gradual decline in several domains of higher cortical function. Both preclinical and clinical research has suggested that the supplementation omega-3 fatty acids (FAs) may have potential benefits for individuals with AD. The present study aimed to identify all randomized controlled trials (RCTs) examining the association between omega-3 FA supplementation and cognitive function in patients with AD, using the Alzheimer's Disease Assessment Scale-Cognitive (ADAS-Cog) Subscale test as the primary outcome measure. A comprehensive search of the PubMed and Cochrane Library databases was conducted for all published RCTs up to December, 2023 that assessed cognition following omega-3 FA supplementation compared to placebo. A total of five studies met the eligibility criteria and were included in the qualitative synthesis, with four of these studies being incorporated into the meta-analysis. From these studies, data were collected from a total of 702 patients with AD, with 376 participants receiving omega-3 FA supplementation and 326 participants receiving a placebo. The primary outcome measure was the ADAS-Cog score. The meta-analysis revealed that omega-3 FA supplementation had a non-significant impact on the ADAS-Cog score compared to placebo, with a mean difference of 1.37 [95% confidence interval (CI) 0.00-2.73]. The heterogeneity among the included studies was moderate (I²=35%, P=0.17). The test for overall effect (z=1.96, P=0.05) indicated no statistical significance. Therefore, it was concluded that omega-3 FA supplementation does not significantly affect the cognitive function of adults with AD.