Prevention of cognitive decline and dementia: Current evidence on lifestyle factors and dietary patterns

Cognitive decline and dementia represent major and growing global health challenges, driven largely by population aging and increased longevity. Currently, more than 55 million people worldwide live with dementia, a figure projected to rise to approximately 153 million by 2050. Alzheimer's disease accounts for the majority of cases, and despite extensive research, effective disease-modifying therapies remain limited. Consequently, increasing attention has shifted toward prevention strategies targeting modifiable risk factors. Accumulating evidence indicates that dementia is not an inevitable consequence of aging and that up to 45 % of cases may be attributable to potentially modifiable lifestyle and environmental factors operating across the life course. Lifestyle behaviors-including diet, physical activity, smoking, alcohol consumption, sleep, and social and cognitive engagement-have emerged as key targets for intervention. In particular, adherence to healthy dietary patterns such as the Mediterranean, DASH, and MIND diets has been associated with better cognitive outcomes, while unhealthy dietary patterns may increase risk. However, findings across studies remain heterogeneous, and uncertainties persist regarding causality, optimal exposure timing, and specific lifestyle components. Recent large prospective cohorts, meta-analyses, umbrella reviews, and multidomain intervention trials have advanced understanding of these associations but have also highlighted important gaps, including limited randomized evidence and underrepresentation of diverse populations. This narrative review critically synthesizes current evidence on lifestyle factors and dietary patterns associated with cognitive decline and dementia risk, focusing on recent high-quality studies. By integrating findings across domains, it aims to clarify areas of consensus and uncertainty, inform prevention strategies, and identify priorities for future research and public health action. See also the graphical abstract(Fig. 1).