Severe tardive dyskinesia (TD) represents a serious and potentially disabling movement disorder, yet relatively little is known about the incidence of and risk factors for severeTD.

We report the results of a longitudinal prospective incidence study of severeTD in 378 middle-aged and elderly neuropsychiatric patients. Psychiatric, neuropsychological, pharmacological and motor variables were obtained at intake and at regular intervals for 36 months.

The cumulative incidence of severeTD was 2.5% after one year, 12.1% after two years, and 22.9% after three years. Individual univariable Cox regression analyses were conducted to identify demographic, psychiatric, motor and pharmacological predictors of severeTD. Results indicated that higher daily doses of neuroleptics at study entry, greater cumulative amounts of prescribed neuroleptic, and greater severity of worsening negative symptoms were predictive of severeTD Conclusions These findings suggest that conventional neuroleptics may be prescribed to older patients only when necessary and at the lowest effective dosage. Additional caution is recommended in patients exhibiting negative symptoms.