Tardive dystonia. Prevalence, risk factors and clinical features.

In order to replicate the results of our previous study of tardive dystonia (TDt) and to enlarge the studied sample, we examined 154 consecutive psychiatric in-patients who had been exposed to neuroleptic drugs for a cumulative period of at least three months. The present study provides further data supporting a distinction between TDt and tardive dyskinesia (TDk). The patients with TDt tend to be younger, male, less exposed to neuroleptic drugs, and to have a more severe movement disorder. TDt appears to be the most frequent form of secondary dystonia, and there is evidence that its prevalence has so far been underestimated.