Which medication is used to decrease chorea in Huntington's disease by decreasing dopamine?

• A. Tetrabenazine (decrease DA)
• B. Amantadine (improve chorea)
• C. Anti-psychotics (reduce depression/anxiety)
• D. AMT 130 (striatum injection)

Answer: (A)

In Huntington’s disease, chorea is driven by excessive dopaminergic activity in the striatum, so lowering the amount of dopamine available for signaling helps reduce these involuntary movements. Tetrabenazine works by inhibiting VMAT2, the transporter that packs dopamine into synaptic vesicles. With VMAT2 blocked, presynaptic stores of dopamine are depleted, less dopamine is released into the synapse, and the hyperkinetic movements of chorea lessen.

Amantadine can improve chorea as well, but its main actions aren’t to decrease dopamine availability; it has dopaminergic-enhancing and NMDA antagonist effects, which can modestly help without directly reducing dopamine stores. Antipsychotics reduce dopamine signaling at receptor sites, which can help with movement symptoms but come with broader side effects and aren’t the mechanism described by “decreasing dopamine.” The AMT 130 approach is not an established standard therapy for this purpose.