Competing physiological pathways link individual differences in weight and abdominal adiposity to white matter...

Area of Science:

• Neuroimaging
• Physiology
• Public Health

Background:

• Obesity is linked to reduced white matter integrity across the brain.
• The physiological systems mediating this association are not fully understood.

Purpose of the Study:

• To investigate if cardiovascular, lipid, glucose, and inflammatory factors mediate the relationship between adiposity and white matter microstructure.
• To identify specific physiological pathways linking body fat to brain structure.

Main Methods:

• Diffusion tensor imaging (DTI) was used to measure white matter microstructure in 155 healthy adults.
• Composite factors for adiposity, cardiovascular health, lipids, glucose, and inflammation were calculated.
• Mediation analyses were performed to assess the role of physiological factors.

Main Results:

• Adiposity (BMI, waist circumference) was associated with reduced white matter integrity (lower FA, higher RD).
• Inflammation and glucose regulation showed global negative associations with white matter.
• Blood pressure and dyslipidemia had localized positive associations with white matter.

Conclusions:

• Physiological factors, particularly inflammation and glucose regulation, significantly mediate the link between adiposity and white matter microstructure.
• Contrasting pathways (global immunity-linked negative, localized vascular-linked positive) explain up to 50% of the adiposity-white matter variance.
• These findings highlight the complex interplay between metabolic health and brain structure in adults.