Objective: To investigate whether dietary patterns (Mediterranean diet (MedDiet), Dietary Approaches to Stop Hypertension (DASH) and A Priori Diet Quality Score (APDQS)) during adulthood are associated with better midlife cognitive performance. Methods: We studied 2,621 CARDIA participants: 45% black, 57% female, and age 25±3.5 years at baseline (1985-6). Diet scores were calculated from repeated diet history up to year 20. Linear models were used to examine association between tertiles of diet score and year 25 to 30 change in standardized test scores for verbal learning (RAVLT), processing speed (Digit Symbol Substitution Test (DSST)) and executive function (Stroop Interference), and Montreal Cognitive Assessment (MoCA) at year 30. Results: Higher scores in all three diets were associated with less decline in verbal memory (all P<0.01). Higher DASH and APDQS scores were associated with less decline on DSST (DASH: low= -0.05, mid= -0.00, high= 0.06; APDQS: low= -0.07, mid= -0.01, high= 0.07, both PTrend=0.02). Higher MedDiet and APDQS scores were associated with less decline on Stroop interference (MedDiet: low=0.10, mid=-0.06, high=-0.03 and APDQS: low=0.11, mid=0.01, high=-0.10, both PTrend<0.01). Odds ratios (95% confidence interval) for poor global cognitive function (≥1 SD below mean MoCA) comparing extreme tertiles of the three dietary scores were 0.45 (0.33-0.62) for MedDiet, 0.38 (0.26-0.54) for APDQS and 0.88 (0.68-1.15) for DASH. Conclusions: Greater adherence to heart-healthy dietary patterns during adulthood was associated with better midlife cognitive performance. Additional studies are needed to define the combination of foods and nutrients for optimal brain health across the life-course.