Within the emerging field of nutritional neuroscience, omega-3 fatty acids are among the most extensively investigated dietary bioactive compounds with potential relevance to cognitive aging. As populations continue to age worldwide, identifying modifiable nutritional factors that support cognitive health has become an important public health priority. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), obtained primarily from marine sources, are integral components of neuronal membranes and serve as precursors of specialized pro-resolving lipid mediators. This narrative review integrates concepts from nutritional neuroscience and geroscience to examine how dietary omega-3 fatty acids may influence biological pathways involved in age-related cognitive decline. Current evidence suggests that DHA and EPA affect multiple processes linked to brain aging, including neuroinflammation, synaptic plasticity, mitochondrial function, oxidative stress, cerebrovascular integrity, cellular senescence, and gut-brain axis signaling. These mechanisms overlap with several hallmarks of aging and may contribute to the maintenance of cognitive function during later life. Observational studies generally associate higher dietary intake or circulating omega-3 status with better cognitive performance and a lower risk of cognitive decline and dementia. Findings from randomized controlled trials are less consistent, although benefits appear more likely in individuals with low baseline omega-3 status, mild cognitive impairment, or increased biological vulnerability. Beyond their established anti-inflammatory effects, omega-3 fatty acids may influence multiple aging-related pathways, particularly inflammaging, vascular aging, and mitochondrial dysfunction. Although heterogeneity in study design, dosage, intervention timing, and participant characteristics precludes firm conclusions, viewing omega-3 fatty acids through a geroscience lens offers a useful framework for interpreting existing evidence and informing future research. Overall, omega-3 fatty acids represent a promising nutritional strategy for supporting cognitive health across the lifespan, warranting further investigation in well-characterized populations and precision nutrition approaches.
