Reduced genual corpus callosal white matter integrity in pathological gambling and its relationship to alcohol abuse or dependence

Objective. Magnetic resonance imaging (MRI) studies have demonstrated functional prefrontal cortical (PFC) abnormalities in pathological gambling (PG) and other psychiatric disorders characterized by impaired impulse control; e. g., cocaine dependence and bipolar disorder. These abnormalities are accompanied by impairments in white matter microstructures in the anterior (genual) corpus callosum (CC) in cocaine dependence and bipolar disorder. Prior studies have not examined white matter integrity in PG. We predicted impairments in genual CC white matter in PG. Methods. Nineteen participants with PG and 19 matched control participants underwent diffusion tensor imaging (DTI) to compare white matter integrity in the CC, as assessed using fractional anisotropy (FA). Results. In PG subjects as compared to control subjects, reduced FA values in the left and right genu of the CC were observed. Multiple regression analyses confirmed that PG status - in addition to age and past alcohol abuse/dependence (AA/AD) - was a significant predictor of genual FA values. Among PG participants, left and right genu FA values were negatively correlated with scores on the Behavioral Activation System Fun-Seeking (BAS-FS) subscale. Limitations. Limitations include a reliance on self-report measures of impulsivity and related constructs and a relatively small sample of PG subjects with past AA/AD. Conclusion. Findings of decreased FA values in the genu of the CC in PG subjects suggest that, like with other disorders of behavioral dyscontrol, white matter microstructural abnormalities contribute to the pathophysiology of PG. These differences appear particularly relevant to individuals with remitted AA/AD, highlighting the importance of considering co-occurring substance use disorders when investigating PG.