Response inhibition in alcohol-dependent patients and patients with depression/anxiety: a functional magnetic resonance imaging study.

BACKGROUND: The inability to inhibit certain behaviors is a key feature of impulsivity, which is often present in people with a substance use disorder. However, the findings on impulsivity in people with alcohol dependence (AD) are inconsistent, possibly because of the frequent co-occurrence of depression/anxiety (D/A) and its influence on impulsivity. In the current study, we aimed to distinguish response inhibition impairments in AD from possible response inhibition effects associated with D/A.
METHOD: AD patients (n = 31) with high D/A co-morbidity were compared to patients with D/A only (n = 18) and healthy controls (HCs; n = 16) using the Stop Signal Task (SST) during functional magnetic resonance imaging (fMRI). Correlation analyses were performed between activated brain areas, behavioral data and addiction and D/A characteristics.
RESULTS: The three groups did not differ on response inhibition performance. However, AD severity, but not D/A severity, was positively associated with decreased response inhibition. During the SST, AD patients showed hyperactivity in the putamen and thalamus compared with D/A patients and HCs. Thalamus activation was negatively associated with AD duration. In addition, AD patients showed hypoactivity in the supplementary motor area (SMA) compared with HCs. SMA activity within HCs was negatively correlated with depressive symptom severity. Discussion In general, AD patients were not more impulsive than D/A patients or HCs but they did reveal inhibition impairments with increasing AD severity. A shift from cortical to subcortical engagement in AD patients during response inhibition may represent an alternative strategy, which decreased with longer drinking history, suggesting the presence of an AD-specific endophenotype.