Dietary approaches to support cognition in older adults: a systematic review

Older adults, particularly those residing in long-term care, experience disproportionate rates of cognitive decline and Alzheimer's disease (AD). While isolated nutrient supplementation has demonstrated limited clinical efficacy, comprehensive whole-food dietary patterns may offer significant neuroprotective benefits through complex nutrient synergy. This systematic review evaluates the efficacy of the Mediterranean, Nordic, Okinawan, and plant-based dietary approaches in mitigating cognitive decline and reducing dementia risk in older populations.

The study protocol was prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO) under the registration ID CRD420261349593. Conducted in accordance with PRISMA 2020 guidelines, a systematic search of PubMed, Web of Science, CINAHL, and ScienceDirect was performed to identify peer-reviewed articles published between January 2021 and the present. Eligible studies included randomized controlled trials (RCT), prospective cohort studies, and longitudinal studies evaluating the impact of whole-food dietary patterns on cognitive outcomes in adults aged 60 and older.

Out of 622 initial records, 16 articles met all inclusion criteria. The synthesized evidence demonstrates that high adherence to these comprehensive dietary patterns is consistently associated with improved memory, enhanced executive function, and a reduced incidence of AD. These cognitive improvements are driven by interconnected physiological mechanisms, including reduced systemic inflammation, improved vascular integrity, favorable shifts in the gut microbiome, and optimized circulating endocannabinoid profiles. Additionally, the magnitude of these benefits is frequently modulated by individual biological factors, such as sex and APOE genotype.

Whole-food dietary patterns provide an effective, evidence-based framework for preserving cognitive resilience compared to single-nutrient interventions. Integrating these nutrient-dense diets into public health initiatives and long-term care settings offers a powerful strategy for neuroprotection, highlighting the need to advance personalized nutrition strategies in future clinical trials.