| Blast-related traumatic brain injury (mbTBI) has become a common consequence of war, potentially affecting as many as 23% of combat soldiers serving in Operation Iraqi Freedom and Operation Enduring Freedom. Obesity in the veteran population is also an escalating problem, and is associated with a multitude of chronic diseases, including diabetes mellitus and cardiovascular disease. Our study aimed to examine the consequences of mbTBI and obesity on the microstructural integrity of white matter (WM) in the brain, and any interaction effects between the two conditions. 28 veterans were included in our analysis. mbTBI subjects had been exposed to at least one explosive blast while in the combat theatre with no additional history of head injury. Weight classification was based upon the World Health Organization ranges, with overweight or obesity defined as a BMI ≥ 25. Diffusion tensor imaging (DTI) was used to measure the fractional anisotropy (FA) of various WM tracts. FA has been used as an indicator of axonal integrity, as research has shown reductions in FA with demyelination, axonal disruption, or cytoskeletal changes. Results indicated main effects for both mbTBI and BMI ≥ 25. For several white matter tracts, FA was lower in subjects with mbTBI. These findings support previous research suggesting a decrease in axonal integrity following TBI. FA was higher in several tracts of overweight/obese subjects compared to normal-weight subjects. We propose that these results could be indicative of changes in membrane lipid metabolism and distribution. While previous research has shown increased WM volume in obese participants, to our knowledge, our study is the first to report higher FA in overweight or obese participants. |
