TD is a movement disorder that develops with longterm neuroleptic use; rarely, especially in the elderly, onset may not be as delayed. TD consists of constant, involuntary, stereotyped choreoathetoid movements most frequently confined to the head and neck musculature. At times, the extremities and respiratory and oropharyngeal musculature are also involved.

Risk factors include long-term treatment with neuroleptics, increasing age, female sex, and the presence of a mood disorder. Although TD is reversible in some cases, it tends to be permanent.

Treatment consists of changing antipsychotics, lowering the dosage, or switching to clozapine.

Clozapine, which appears to work by a different mechanism from other antipsychotics, may reduce or eliminate the abnormal movements of TO.