Brain structure and obesity.
Level 4 - case-series / case-control
Cross-sectional structural neuroimaging analysis within an observational cohort
PubMed 19662657 · doi:10.1002/hbm.20870
What was done
Tensor-based morphometry was used to assess gray matter and white matter volume differences in 94 elderly subjects who remained cognitively normal for at least 5 years following baseline scanning. The authors performed bivariate analyses, false-discovery-rate-corrected multiple regression, and ANCOVA models adjusting for age, gender, and race to test associations of body mass index, fasting plasma insulin, and Type II diabetes mellitus with regional brain atrophy across BMI categories.
What was found
Bivariate analyses linked BMI, fasting plasma insulin, and diabetes with atrophy in frontal, temporal, and subcortical regions. In multiple regression models, BMI remained negatively correlated with brain volume (FDR < 5%), while diabetes and fasting insulin were no longer significantly associated with volume differences. On ANCOVA, obese subjects (BMI > 30) showed atrophy in the frontal lobes, anterior cingulate gyrus, hippocampus, and thalamus compared with normal-BMI subjects (18.5-25), while overweight subjects (BMI 25-30) showed atrophy in the basal ganglia and corona radiata. Overall brain volume did not differ between overweight and obese groups. Exact numerical effect sizes and volume values were not reported in the abstract.
Why it matters
This study shows that excess body weight is linked to detectable regional brain atrophy in older adults even in the absence of cognitive impairment.
Limits
The study is limited by a modest sample size of 94 elderly participants and a cross-sectional imaging design that cannot establish causality or rate of loss over time. The abstract reports significance thresholds but no absolute effect sizes, volumetric numbers, or confidence intervals.
Cited by
- supports A brain imaging study by Cyrus Raji showed that overweight individuals had 4% less brain volume and obese individuals had 8% less brain volume compared to normal-weight individuals.