By Mary Henderson
Researchers at Beijing Friendship Hospital provided evidence of a causal relationship between body mass index (BMI) and brain health Sunday afternoon in the Learning Center.
“Obesity is a worldwide problem,” said Jia Li, PhD, Department of Radiology, Beijing Friendship Hospital. “Although the relationship between BMI and poor cardiovascular health is well-known, the causal relationship between BMI and brain has been unclear.”
Dr. Li, who conducted the study with Han Lv, MD, presented the results from a 16-year population-based, longitudinal study aimed at demonstrating the effects of cumulative BMI on neuroimaging features in adults.
For the study, the team collected clinical data on 1,074 subjects (ages 25-83) between 2006 and 2018. The mean age and BMI were 55.2 and 25, respectively. Subjects with evidence of dementia or mental disorders and diagnosed cancer were excluded.
The cohort included 420 subjects with a normal BMI (18.5-24 kg/m2), four who had low BMI (<18.5 kg/m2), 488 subjects who were overweight (24-28 kg/m2) and 162 subjects with obesity (>=28 kg/m2).
High-resolution MR morphological imaging and diffusion tensor imaging was performed on subjects between 2020 and 2022 to collect volumetric measurements of the brain structure, white matter hyperintensity (WMH) and white matter microstructural integrity.
The researchers modeled the subjects’ 16-year trajectories to evaluate cumulative exposure to high BMI. They also used an innovative method to calculate brain aging based on the regressing volume of cerebral parenchyma.
“This allowed us to estimate the time necessary for participants with a high BMI to achieve the same cerebral parenchyma volume as those with a BMI within normal range,” Dr. Li said.
“We found that high BMI was associated with a wide range of negative brain health effects,” Dr. Li said. “High BMI is causally associated with smaller brain volume, a larger volume of white matter lesions, and abnormal microstructural integrity in projection fibers, especially in young adults.”
For adults under 45, the difference in cerebral parenchyma volume between subjects with high BMI and those with normal BMI corresponded to 12 years of brain aging.
The team also conducted a two-sample randomization association using body mass index phenotypes from 681,275 individuals and neuroimaging-derived phenotypes from 33,224 individuals to establish the causal relationship between genetic determinants of high BMI and neuroimaging features.
Results of this analysis indicated causal relationships between high BMI and smaller volumes of cerebral parenchyma and gray matter, and higher fractional anisotropy in projection fibers.
Co-researcher Dr. Lv said the results were in line with the findings of their longitudinal study cohort.
“We recommend paying more attention to the BMI, especially the negative effect of the cumulative exposure to high BMI,” said Dr. Lv. “For adults younger than 45 years, BMI should be maintained below 26.2 kg/m2 for better brain health.”
Access the presentation, “Association Between Body Mass Index and Brain Aging in Adults: A 16-Year Population-Based Cohort and Mendelian Randomization Study,” (S3B-SPNR-9) on demand at RSNA.org/MeetingCentral.
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The RSNA 2024 Daily Bulletin is the official publication of the 110th Scientific Assembly and Annual Meeting of the Radiological Society of North America. Published online Sunday, December 1 — Friday, December 6.
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