Dyskinesia is best defined as which of the following?

• A. Loss of memory due to aging.
• B. Uncontrolled laughter due to brain injury.
• C. Abnormality or impairment of voluntary movement. Associated with antipsychotic medications.
• D. Rapid heart rate after exercise.

Answer: (C)

Dyskinesia refers to abnormal, involuntary movements or impaired control of voluntary movements. This condition often arises as an extrapyramidal side effect of long-term dopamine-blocking antipsychotic medications, which disrupt the basal ganglia circuits that coordinate smooth movement, leading to choreiform or dystonic movements. The other options describe memory loss, inappropriate laughter, or rapid heart rate—none of which capture the movement abnormality that dyskinesia denotes.