The relationship between microstructural alterations of the brain and clinical measurements in children and adolescents with hair pulling disorder.

Several studies have evaluated gray matter abnormalities and white matter integrity in adults with hair pulling disorder (HPD). However, no prior studies have defined the relationship between neuroimaging parameters and clinical measurements in children and adolescents with HPD. The purposes of this study were to determine the correlation between magnetic resonance imaging (MRI) indices and clinical measurements in children and adolescents with HPD, and to compare HPD patients with age- and sex- matched healthy controls (HC). Pediatric HPD patients (n = 9) and HC subjects (n = 10), aged 9-17 years, were recruited. Three-dimensional T1-weighted structural MRI (3D T1W) and diffusion-tensor imaging (DTI) scans were obtained for each subject. Gray matter and white matter volumes were calculated from 3D T1W. Fractional anisotropy (FA) and average diffusion coefficients (Dav) were mapped from DTI. Voxel-based and region-of-interest correlations between MRI indices and clinical measurements were analyzed. In addition, two-sample t-tests were used to compare voxel-based tissue volumes, FA, and Dav maps between the two groups. Alterations in both brain tissue volume and white matter integrity were associated with symptom severity, especially in the precuneus, anterior cingulate, temporal cortex, and frontal cortex regions. FA values in HPD patients were significantly higher than those observed in HC subjects, particularly in the cerebellum and cuneus regions. Alterations of brain tissue volumes and microstructural changes are associated with severity of clinical symptoms in children and adolescents with HPD. Fractional anisotropy is the most sensitive method to distinguish pediatric HPD patients from healthy children. The results of this study can facilitate use of MRI indices to follow the transition from pediatric HPD to adult HPD.