By Jennie McKee
During a scientific session held yesterday, Mahsa Dolatshahi, MD, MPH, presented research linking higher amounts of visceral fat in middle-aged people to reduced cortical thickness.
This observed reduction can contribute to Alzheimer disease later in life, according to Dr. Dolatshahi, an intern at Missouri Baptist Medical Center and incoming radiology resident at Mallinckrodt Institute of Radiology, both in St. Louis.
Dr. Dolatshahi noted that obesity is recognized as the top modifiable risk factor for dementia in the United States. The most common definition of obesity is having a body mass index (BMI) of 30 kg/m2 or higher; however, recent evidence has shown that BMI doesn’t specifically represent visceral adiposity.
“Visceral adiposity is associated with insulin resistance and systemic inflammation, the mechanisms also involved in dementia,” she said. “We aimed to investigate the role of visceral fat versus subcutaneous fat, insulin resistance and high-density lipoprotein levels, as well as social determinants of health and how they relate to cortical thinning in the brain.”
“We aimed to investigate the role of visceral fat versus subcutaneous fat, insulin resistance and high-density lipoprotein levels, as well as social determinants of health and how they relate to cortical thinning in the brain.”
Mahsa Dolatshahi, MD, MPH
The study included 118 cognitively normal individuals who, as described in the context of Alzheimer’s disease, showed no clinical evidence of cognitive impairment and function independently in daily life. The average age of study participants was 49 years, and two-thirds were female. More than half of the participants were classified as obese with an average BMI of 32.46 kg/m2. Each participant underwent metabolic assessment as well as brain and body MRI.
Dr. Dolatshahi and colleagues performed automatic segmentation of cortical and subcortical brain regions using a probabilistic atlas, followed by visual inspection and manual editing as needed. They also used in-house software to semi-automatically segment visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), applying manual editing to refine these results.
They used the Spearman correlation rank test to assess how cortical thickness in late-onset Alzheimer disease (LOAD) regions relates to several key factors. These included BMI, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), VAT, SAT and lipid profile. Age and sex were considered as covariates in the analysis, and BMI was also used as a covariate to determine whether these associations were independent of overall BMI.
The researchers found that participants with obesity had significantly increased VAT, SAT, HOMA-IR as well as lower high-density lipoprotein (HDL). Among the LOAD regions, higher BMI correlated to cortical thinning in the right percutaneous, superior parietal, lateral occipital, left transverse temporal and temporal pole, after correction for multiple comparisons.
In addition, they found that greater amounts of VAT were associated with lower cortical thickness in the right posterior cingulate, parahippocampal and fusiform areas, as well as the left entorhinal, middle temporal, superior temporal and temporal pole. Notably, this link was independent from BMI.
Dr. Dolatshahi emphasized that image-derived measurements of body composition could play a crucial role in opportunistic screening for dementia and subsequent interventions to modify body composition. She and her team were surprised to see that the association between visceral fat and cortical thinning in different brain regions persisted even after adjusting for BMI, while subcutaneous fat, insulin resistance or lipid profile effects are dependent on BMI.
“These results show the importance of effective weight loss, with a focus on visceral fat loss, for prevention of dementia and cortical thinning,” Dr. Dolatshahi said.
Access the presentation, “Midlife MR-Derived Visceral Adiposity is Linked to Cortical Thinning Independent from Body Mass Index,” (W1-SSM03-3) on demand at RSNA.org/MeetingCentral.
© 2025 RSNA.
The RSNA 2025 Daily Bulletin is the official publication of the 110th Scientific Assembly and Annual Meeting of the Radiological Society of North America. Published online Sunday, November 30 — Thursday, December 4.
The RSNA 2025 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Suite 200, Oak Brook, IL 60523.
