Patterns of Regional Cerebral Blood Flow as a Function of Obesity in Adults.
Level 4 - case-series / case-control
Cross-sectional observational study analyzing imaging data across BMI categories
PubMed 32773393 · doi:10.3233/JAD-200655
What was done
The authors analyzed 35,442 brain SPECT scans from a cross-sectional cohort of 17,721 adults (mean age 40.8 ± 16.2 years, range 18–94 years) imaged at a psychiatric clinic. Scans were captured at resting baseline and during a concentration state following the Connors Continuous Performance Test II. Perfusion was quantified across 128 brain regions using the Automated Anatomical Labeling atlas and compared via ANOVA across five BMI categories: underweight (<18.5), normal weight (18.5–24.9), overweight (24.9–29.9), obesity (≥30), and morbid obesity (≥40).
What was found
Higher BMI was associated with decreased cerebral perfusion on both resting and concentration SPECT scans across adulthood. These perfusion decreases occurred across virtually all evaluated brain regions, including areas implicated in Alzheimer's disease such as the hippocampus. The abstract reports no specific numerical effect sizes, test statistics, or p-values.
Why it matters
This study provides evidence in a very large sample that elevated BMI is linked to widespread reductions in cerebral blood flow, pointing to potential neurovascular mechanisms linking obesity to cognitive decline and dementia.
Limits
The sample is derived entirely from a psychiatric cohort, which may not generalize to the general healthy population. The cross-sectional design cannot establish causality or directionality. The abstract does not provide numerical effect sizes, confidence intervals, or details on adjustments for critical confounders such as cardiovascular risk factors, psychiatric diagnoses, or psychotropic medications.
Cited by
- context A study by Daniel Amen in the Journal of Alzheimer's Disease found that overweight and obese NFL players had lower blood flow in the prefrontal cortex compared to normal-weight players.
- supports A published study by Daniel Amen examining 35,000 brain scans found a linear correlation where higher body weight was associated with decreased blood flow across virtually every brain region.