Extrapyramidal symptoms in substance abusers with and without schizophrenia and in nonabusing patients with schizophrenia

Extrapyramidal symptoms (EPS) such as parkinsonism, dystonia, dyskinesia, and akathisia are conditions of impaired motor function, which are associated with chronic antipsychotic treatment in schizophrenia. In addition, EPS is often exacerbated by psychoactive substance (PAS) abuse, which is frequently observed in this population. Few studies, however, have investigated the contribution of PAS abuse on EPS in PAS-abusers without comorbid psychosis. This study compared the occurrence of EPS in outpatient schizophrenia patients with (DD group; n 5 36) and without PAS abuse (SCZ group; n 5 41) as well as in nonschizophrenia PAS abusers undergoing detoxification [substance use disorder (SUD) group; n 5 38]. Psychiatric symptoms were measured using the Positive and Negative Syndrome Scale and the Calgary Depression Scale for schizophrenia. Extrapyramidal symptoms were evaluated with the Extrapyramidal Symptoms Rating Scale and the Barnes Akathisia Scale. SUD diagnoses were complemented with urine drug screenings. We found that DD patients exhibited significantly more parkinsonism than SCZ patients. Our subanalyses revealed that cocaine and alcohol abuse/dependence was responsible for the increase in parkinsonism in DD patients. Additionally, we found that SUD individuals exhibited significantly more akathisia than SCZ patients. In these latter individuals, subanalyses revealed that alcohol and cannabis abuse/dependence was responsible for the increase in akathisia. Our results suggest that PAS abuse is a contributor to EPS in individuals with and without schizophrenia.