Obsessive-compulsive symptoms in Parkinson's disease

To systematically investigate obsessive-compulsive traits in Parkinson's di sease, patients were administered the Maudsley obsessional-compulsive inven tory (MOCI) and a modification of the Leyton obsessional inventory (LOI) to a sample of non-demented and non-depressed patients with Parkinson's disea se. Patients with severe Parkinson's disease showed more obsessive traits t han normal controls in MOCI and LOI total scores, and in the "checking", "d oubting", and "cleaning" subscales of the MOCI. By contrast, patients with mild disease did not differ from controls. A significant correlation was fo und between severity and duration of illness and MOCI total score. These re sults support the involvement of basal ganglia in obsessive-compulsive symp tomatology. As patients with mild Parkinson's disease did not differ from c ontrols, obsessive-compulsive disorder does not seem to be directly related to the initial nigrostriatal dopaminergic deficiency which causes clinical Parkinson's disease symptomatology. The appearance of obsessive symptoms c ould be related to the subset of neurochemical changes taking place at the level of the basal ganglia circuitry as disease progresses.