"Habit" gambling behaviour caused by ischemic lesions affecting the cognitive territories of the basal ganglia.

We report the case of a patient suffering from sudden apathy and pathological gambling-like behaviour after bilateral ischemic lesions involving the dorsal portion of the head of the caudate nuclei and adjacent anterior limb of the internal capsules. This is the first report of the association of an apathy and abnormal gambling behaviour following a stroke affecting sub-cortical structures. Although the location of the lesions, affecting the dorsal striatum, may explain the emergence of an apathetic state, it is, however, at first sight, not easy to explain the gambling behaviour because the patient was normal in tests evaluating sensitivity to reward, and no radiological abnormality was found in the cortical-sub-cortical system of reward. It is proposed that, for this patient, the mechanism of maladaptive gambling behaviour was the development of a routine behaviour related to the patient's cognitive inertia, a mechanism different from the changes in reward sensitivity observed after damage to the orbital ventral prefrontal-ventral striatum system or in dopamine dysregulation syndrome in Parkinson's disease.