Interrelations between psychiatric symptoms and drug-induced movement disorder.

After 30 years of clinical research into drug-induced movement disorder (DIMD), we are still facing unresolved issues regarding the interrelations between psychiatric symptoms and DIMD. Recently, I proposed a new classification of DIMD that includes abnormal movements previously labelled extrapyramidal symptoms. DIMD caused by psychotropic drugs is still confused with psychiatric symptoms treated by the same drugs. The results from 2 international multicentre trials, the InterSePT and the Ris-Consta Studies, conducted in the era of both typical and atypical antipsychotic agents, which included over 3,000 patients with schizophrenia and schizoaffective disorder worldwide, still showed a high, but decreasing, incidence of pretreatment DIMD, which varied from 57.5% (1998-1999) to 47.4% (1999-2000), and a decreasing incidence of tardive dyskinesia, which varied from 12% (1998-1999) to 10.2% (1999-2000), reflecting the greater use of atypical antipsychotic drugs. Furthermore, in both studies, psychiatric symptoms as measured by the Positive and Negative Symptom Scale (PANSS) were significantly correlated with DIMD and DIMD subtypes, thus suggesting the need for additional measurement instruments in schizophrenia and related psychoses.