Harvard Study of 159,347 Finds DASH Diet Cuts Cognitive Decline Risk 41%
Updated
Updated · ScienceAlert · Jun 27
Harvard Study of 159,347 Finds DASH Diet Cuts Cognitive Decline Risk 41%
3 articles · Updated · ScienceAlert · Jun 27
Summary
159,347 participants tracked for about 30 years showed the strongest brain-health association with the DASH diet, with top adherents facing a 41% lower risk of subjective cognitive decline than the least adherent.
Six dietary patterns all showed benefits, but DASH stood out: strict followers gained nearly twice the benefit seen with other diets and scored 0.76 years younger on cognitive aging tests and 1.37 years younger on working-memory tests.
The runner-up diets were notably weaker, with plant-based and hyperinsulinemia indexes each linked to a 24% lower risk, the Planetary Health Index to 20%, and the Mediterranean-like AHEI-2010 plan to 16%.
Researchers said the association remained visible up to 26 years before assessment and was especially strong in midlife, reinforcing evidence that long-term eating patterns tied to lower salt, less red meat and less sugar may help protect the aging brain.
The JAMA Neurology study was observational, so it cannot prove DASH prevents dementia or Alzheimer's, but it adds to growing evidence that heart-healthy diets may also support cognitive health.
Why isn't the world's best diet for brain health more widely followed?
With diet's link to brain health proven, is personalized nutrition next?
Can your diet stop a common virus from triggering Alzheimer's disease?
DASH Diet Cuts Cognitive Decline Risk by 41%: Landmark 30-Year Harvard Study Reveals Brain Health Benefits
Overview
A major Harvard study published in 2026 followed over 150,000 people for 30 years and found that heart-healthy diets, especially the DASH diet, are strongly linked to better long-term brain health. Researchers scored participants’ diets based on how closely they matched six healthy eating patterns, all high in fish and vegetables and low in red meats and sugary foods. The results showed that those who followed these diets, particularly DASH, had improved cognitive health as they aged. This suggests that making healthy food choices can play a key role in keeping the brain sharp over time.