Individual differences in fornix microstructure and body mass index

Area of Science:

• Neuroscience
• Radiology
• Gerontology

Background:

• Rising obesity rates are a global health concern.
• Obesity is linked to hippocampal dysfunction, potentially affecting appetite regulation.
• The hippocampus communicates with key brain regions for food intake control via the fornix tract.

Purpose of the Study:

• To investigate the relationship between fornix microstructural properties and Body Mass Index (BMI) variations.
• To examine these associations in community-dwelling older adults across normal and overweight ranges.

Main Methods:

• Diffusion MRI tractography was used to analyze fornix white matter microstructure.
• Body Mass Index (BMI) was measured in older adults aged 53-93 years.
• Analyses controlled for age, education, cognitive performance, blood pressure, and global brain volume.

Main Results:

• Higher BMI correlated with increased axial and mean diffusivity in the fornix.
• These associations were stronger in overweight individuals.
• No similar associations were found in the parahippocampal cingulum, a control pathway.

Conclusions:

• Microstructural changes in the fornix are associated with increasing BMI, even within normal to overweight ranges.
• These findings are not exclusive to obesity.
• The fornix may be crucial for hippocampal-hypothalamic-prefrontal network function in food intake control and can reflect weight gain.