Valbenazine may cause which of the following neurological adverse effects?

• A. Drowsiness and fatigue only
• B. Acute dystonia
• C. Akathisia
• D. Hyperglycemia

Answer: (C)

Valbenazine lowers dopamine release in the brain by inhibiting VMAT2, which helps reduce tardive dyskinesia but can also disrupt dopaminergic signaling in the nigrostriatal pathway. This disruption can manifest as akathisia, a subjective feeling of inner restlessness with an urge to move and often visible as pacing or inability to stay still. Among the neurological effects listed, akathisia is the classic movement-related side effect associated with VMAT2 inhibitors like valbenazine. Drowsiness or fatigue can occur too, but they are not the specific motor disturbance described here, and hyperglycemia is not a neurological adverse effect. Therefore, akathisia best fits the question.