Body Satisfaction, Exercise Dependence, and White Matter Microstructure in Young Adults.

Background: Self-body satisfaction is considered a psychological factor for exercise dependence (EXD). However, the potential neuropsychological mechanisms underlying this association remain unclear.

Purpose: To investigate the role of white matter microstructure in the association between body satisfaction and EXD.

Study Type: Prospective.

Population: One hundred eight regular exercisers (age 22.11 ± 2.62 years; 58 female).

Field Strength/sequence: 3.0 Tesla; diffusion-weighted echo planar imaging with 30 directions.

Assessment: The Body Shape Satisfaction (BSS) and Exercise Dependence Scale (EDS); whole-brain tract-based spatial statistics (TBSS) and correlational tractography analyses; average fractional anisotropy (FA) and quantitative anisotropy (QA) values of obtained tracts.

Statistical Tests: The whole-brain regression model, mediation analysis, and simple slope analysis. P values <0.05 were defined as statistically significant.

Results: The BSS and EDS scores were 37.33 ± 6.32 and 68.22 ± 13.88, respectively. TBSS showed negative correlations between EDS and FA values in the bilateral corticospinal tract (CST, r = -0.41), right cingulum (r = -0.41), and left superior thalamic radiation (STR, r = -0.50). Correlational tractography showed negative associations between EDS and QA values of the left inferior frontal occipital fasciculus (r = -0.35), STR (r = -0.42), CST (r = -0.31), and right cingulum (r = -0.28). The FA values, rather than QA values, mediated the BSS-EDS association (indirect effects = 0.30). The BSS was significantly associated with the EDS score at both low (β = 1.02) and high (β = 0.43) levels of FA value, while the association was significant only at the high level of QA value (β = 1.26).

Data Conclusion: EXD was correlated with white matter in frontal-subcortical and sensorimotor networks, and these tracts mediated the body satisfaction-EXD association. White matter microstructure could be a promising neural signature for understanding the underlying neuropsychological mechanisms of EXD.

Level Of Evidence: 2 TECHNICAL EFFICACY: Stage 1.