Association of Obesity With Cognitive Decline

There are disparities in the prevalence of obesity by race and the relationship between obesity and cognitive decline is unclear. The objective of this study was to determine whether obesity is independently associated with cognitive decline and if the association between obesity and cognitive decline differs in Black and White adults. We hypothesized that obesity is associated with greater cognitive decline compared to normal weight, and that the impact of obesity on cognitive decline is more pronounced in Black adults compared to their White counterparts.

We pooled data from 28,867 participants free of stroke and dementia (mean, standard deviation [SD]: age 61 [10.7] years at the first cognitive assessment, 55% female, 24% Black, and 29% obese) from six cohorts. The primary outcome was annual change in global cognition. We performed linear mixed-effects models with and without time-varying cumulative mean systolic blood pressure (SBP) and fasting plasma glucose (FPG). Global cognition was set to a t-score metric (mean 50, standard deviation [SD] 10) at a participants first cognitive assessment; a 1-point difference represents a 0.1 SD difference in global cognition across the six cohorts. The median follow-up was 6.5 years (25th percentile, 75th percentile: 5.03, 20.15).

Obese participants had lower baseline global cognition than normal-weight participants (difference in intercepts, -0.36 [95% CI, -0.46 to -0.17]; P<0.001). This difference in baseline global cognition was attenuated but was borderline significant after accounting for SBP and FPG (adjusted differences in intercepts, -0.19 [95% CI, -0.39 to 0.002]; P=0.05). There was no difference in the rate of decline in global cognition between obese and normal-weight participants (difference in slope, 0.009 points/year [95% CI, -0.009 to 0.03]; P=0.32). After accounting for SBP and FPG, obese participants had a slower decline in global cognition (adjusted difference in slope, 0.03 points/year slower [95% CI, 0.01 to 0.05]; P<0.001). There was no evidence that race modified the association between BMI and global cognitive decline (P=0.34).

These results suggest that obesity is associated with lower initial cognitive scores and may potentially attenuate declines in cognition after accounting for BP and FPG.

 

Sherry