Healthy dietary habits help prevent cognitive decline with ageing

A healthy diet, defined by adherence to either the Mediterranean diet, the World Health Organization (WHO) guidelines, or Dutch Health Council dietary guidelines, is predictive of better cognitive function and slower cognitive decline with ageing from middle age onward, a study has shown.

A total of 3,644 participants (51 percent female) aged 45–75 years at baseline were included in this population-based longitudinal study. The authors assessed global cognitive function, memory, processing speed, and cognitive flexibility at 5-year time intervals up to 20-year follow-up.

Adherence to the Mediterranean diet, the WHO dietary guidelines, and the Dutch Health Council dietary guidelines 2015 was measured using the modified Mediterranean Diet Score (mMDS), the Healthy Diet Indicator (HDI), and the modified Dutch Healthy Diet 2015 index (mDHD15-index), respectively.

The authors classified the scores on the dietary indices in tertiles (low, medium, high adherence). They also used linear mixed models to demonstrate the level and change in cognitive function by adherence to healthy diets.

The highest tertiles of the mMDS, HDI, and mDHD15-index significantly correlated with better cognitive function than the lowest tertiles (p<0.01), for instance at age 65 years equivalent to being 2 years younger in terms of global cognition.

The highest tertiles of the mMDS, HDI, and mDHD15-index were also associated with 6–7-percent slower cognitive decline from age 55–75 years, as well as slower decline in processing speed (mMDS: 10 percent, 95 percent confidence interval [CI], 2–18; mDHD15: 12 percent, 95 percent CI, 6–21) and cognitive flexibility (mDHD15: 10 percent, 95 percent CI, 4–18).

“Diet, in particular the Mediterranean diet, has been associated with better cognitive function and less cognitive decline in older populations,” the authors noted.