Effects Of Obesity, Weight Loss, And Physical Activity On Brain Structure And Cognition

Abstract

Obesity has been related to altered brain structure and cognitive function in adults, leading to speculation that weight loss may favorably influence these measures. However, evidence of the impact of weight loss on cognition and brain gray matter volume has been inconsistent due to small sample sizes and short duration interventions. There is also limited data on middle-aged adults with overweight or obesity. PURPOSE: To examine the associations between body weight, physical activity (PA), cognition, and brain structure in adults with overweight or obesity. METHODS: Participants (N = 115, Age = 48 years [IQR: 42, 52], BMI = 32.4 kg/m2 [IQR: 29.0, 35.4]) were randomized to diet-only, diet plus 150 min/week of MVPA, or diet plus 250 min/week of MVPA groups. All groups were prescribed a reduced-calorie diet (1200-1800 kcal/day) with behavioral intervention sessions. Assessments of body weight, PA, cognitive function, and gray matter volume were performed and only participants that completed baseline and 12-month assessments were included. PA (MET-min/wk of light-intensity (LPA) and moderate-to-vigorous intensity (MVPA)) was measured objectively. Working memory (reaction time (RT)) was assessed using the N-Back test. Bilateral gray matter volumes (mm3) of the hippocampus and basal ganglia were measured using 3 T magnetic resonance imaging and calculated using FSL segmentation algorithms. RESULTS: The intervention resulted in a significant decrease in weight, one-back RT, two-back RT, with increases in LPA and MVPA. Few significant associations were found between weight or PA and cognitive function or gray matter volume at baseline and across the intervention. Greater weight loss was associated with increases in bilateral pallidum volume (β = -5.95, p = .046). Higher baseline MVPA was associated with larger bilateral nucleus accumbens volume (β = .044, p = .008). Change in LPA was associated with differences (absolute and percent) in RT (β = -.027, p = .025; β = -.003, p = .043), suggesting LPA was associated with improved performance. CONCLUSION: In the context of a behavioral weight loss intervention, findings show a favorable, but small, effect of weight loss and PA on selective cognitive and volumetric outcomes in middle-aged adults with overweight or obesity.Supported by NIH Grants R01 HL096770 and R01 DK095172