Despite the suggestion that impulsivity plays a central role in the transfer from a recreational drug use to a substance use disorder, very few studies focused on neurobiological markers for addiction. This study aimed to identify volumetric alterations in a sample of patients with mild alcohol use disorder with a short history of alcohol use, compared with a control group, and also focused on its association with impulsivity levels. Most magnetic resonance imaging studies have focused on severe alcohol use disorder, formerly called alcohol-dependent patients, showing alcohol-related structural alterations and their association with alcohol use history variables but not with personality parameters like impulsivity. Our hypothesis is that our group of alcohol users may already display structural alterations especially in brain regions related to inhibitory control like medial-prefrontal regions, and that those structural alterations could be more associated to personality traits like impulsivity than to drug use variables. Our results clearly demonstrate that our population showed lower regional grey and white matter volumes in the medial-prefrontal and orbitofrontal cortices, as well as higher regional white matter volume in the ventral striatum and the internal capsule. Volumetric alterations were associated to the Barratt's impulsivity score: the more impulsive the subjects, the lower the medial-prefrontal cortex grey matter volume.
Twenty-four patients meeting DSM-IV criteria for alcohol abuse completed the Barratt Impulsiveness Scale and MRI scans were performed for voxel-based morphometry. Lower medial prefrontal cortex (mPFC) grey matter regional volume is correlated with higher impulsivity scores in alcoholic patients. A lower white matter (WM) regional volume underlying mPFC and Orbitofrontal cortex is also found in alcoholic patients. Interestingly, an increased WM volume is found at telencephalic fascicles of ventral striatum. These results give morpho-functional support to the chatracteristic lack of of control over emotional and compulsive behaviors described in these patients.