Chronic use of phenothiazines is most commonly associated with which movement disorder?

• A. Tardive dyskinesia
• B. Parkinson's disease
• C. Huntington's disease
• D. Tourette's syndrome

Answer: (A)

Chronic blockade of dopamine D2 receptors in the nigrostriatal pathway by phenothiazines leads to tardive dyskinesia, a hyperkinetic movement disorder. With long-term antipsychotic use, the brain can become supersensitive to dopamine or upregulate receptors, producing involuntary, repetitive movements. These are often orofacial—grimacing, lip smacking, tongue movements—and may involve the limbs and trunk; the key point is that these movements can persist even after stopping the medication. While antipsychotics can cause drug-induced parkinsonism in the short term, tardive dyskinesia is the classic chronic complication associated with prolonged phenothiazine exposure. Huntington's disease and Tourette's syndrome have distinct etiologies and clinical patterns that are not linked to chronic phenothiazine use.