Healthy diet and cognition in Finnish adults: a comparison of Mediterranean, Nordic, and MIND diets

Abstract Background Cognitive decline and dementia are major public health challenges in aging societies, and lifestyle factors play a key role in their prevention. Evidence supports the association between healthy diets and better cognitive performance, but most previous studies have focused on older individuals. We studied how diet quality associates with cognition and how age modifies this association in a sample with a wide age range. Methods We analysed diet and cognition both cross-sectionally and longitudinally in a population-based sample aged 30 to 100 years from the Health 2000/2011 study. Diet quality was assessed using a validated food frequency questionnaire, and a priori scores were calculated to reflect adherence to the Mediterranean, Nordic, and MIND diets. Selected tests from the CERAD battery were summarised into a global cognition score at baseline and after 10-year follow-up. For interaction analyses, age was categorised into tertiles. Results Of the 5853 participants in cross-sectional analysis (mean age 53; 55% women) 3589 (61%) participated in follow-up. Higher baseline age, lower cognition, and unhealthier diet predicted dropout. All three diets were positively associated with baseline cognition (p < 0.001 for trend across quartiles) and predicted 10-year cognitive change (p < 0.05). Age modified the cross-sectional association (age*diet interaction p < 0.01), with significant associations observed in the highest tertiles, but not in participants under 45 years. Age did not modify the association between diet and cognitive change. Conclusions Adherence to the Mediterranean, Nordic, or MIND diet was similarly associated with better cognitive performance both at baseline and over time. Cross-sectional associations appeared stronger in older age groups, but age did not modify the association between diet and long-term cognitive change. Further studies are needed to clarify significance of these findings for dementia prevention. Key messages • Variety of healthy diets have potential to support cognitive health: Mediterranean, Nordic, and MIND diets show similar positive associations with cognitive performance in general population. • The cross-sectional association between adherence to healthy diets and better cognition is stronger in older age groups, but diet predicts longitudinal cognitive change similarly in all ages.