Antipsychotic drugs are frequently used to treat chorea and several behavioral and psychiatric symptoms of HD including irritability, aggressive, agitation and psychotic symptoms. While they should be reserved for the more severe psychiatric and behavior symptoms, they should not be inappropriately feared. They can improve and indeed save lives. Of the drugs available, the second generation antipsychotic drugs are usually preferred over first generation drugs (like haloperidol) because they have fewer Parkinsonism side effects.

Dosing information is given so that you will learn about dosing ranges for each drug. Specific recommendation for any individual must be made by your treating doctor.

Haloperidol (Haldol®) This is an“old” drug. When possible, newer drugs with fewer side effects are preferred. Even so, this drug should not be considered a poison. It is a lot better than nothing when cost makes it the only treatment option. This drug is also frequently prescribed for chorea. However, at least in the U.S. several of the newer drugs are now generic, most will be covered under most insurance plans (including Medicare and Medicaid).

Aripiprazole (Abilify®) This one is not generic yet, but recent study suggests that this drug may be as effective as tetrabenazine for the treatment for chorea, but with fewer side effects [Brusa L 2009]. Lower doses of 5 to 10 mg per day is usually sufficient for treatment of chorea. The dose may need to be higher for psychotic symptoms, starting at 10 to 15 mg once daily, and may be increased to 30 mg for psychosis. The most common side effects are headache, nausea, vomiting, restlessness, tremor, and constipation. Studies suggest that weight gain is less than with several other antipsychotic drugs.

Quetiapine (Seroquel®) Based on studies in Parkinson’s, this is the drug that may be preferred for many symptoms of Huntington’s because it appears to cause less bradykinesia (slowness of movement) that is already present in HD [Tarsy D 2002] [Miyasaki JM 2006]. This is true even when used at high doses. The usual starting dose is 25 mg (twice daily), which can be increased up to a maximum of 300 mg (twice daily). Lower doses should be used in the elderly. The main side effects are sleepiness (which may improve after several days), low blood pressure (light-headedness), restlessness, dry mouth, and weight gain.

Clozapine (Clozaril®) Though this drug has low side effects of worsening bradykinesia (slowness of movement), it is infrequently used because it can damage bone marrow. If this drug is used, it must be monitored with weekly (or biweekly) blood testing for at least 6 months. It appears to have no or limited effect on chorea. This drug is used only when other drugs fail.

Risperidone (Risperdal®) This drug is the most widely prescribed of the antipsychotics. It is typically dosed once daily, starting at 1 to 2 mg/day, increasing as needed up to 6-8 mg/day. Dosage for the older person should start much lower at 0.25 to 0.50 mg/day. The primary side effects are sleepiness, low blood pressure, restlessness, breast stimulation and weight gain. Higher doses are associated with worsening of rigidity and slowness of movements.

Olanzapine (Zyprexa®) This drug is usually given once a day, starting at 5 to 10 mg/day; increasing as needed up to 30 mg to 40 mg/day. This drug can cause worsening of rigidity and slowness of movement. Weight gain is a prominent side effect of this drug. Others include sleepiness, restlessness, low blood pressure, dry mouth, and constipation.

Ziprasidone (Geodon®) This drug is dosed once or twice daily starting with 20 to 40 mg/day, and increasing up to 160 mg/day as needed. More care must be taken with this drug because absorption doubles when taken with food, and there are several drug interactions. It is marketed as having less risk of weight gain than other atypical drugs. Side effects associated include mild sedation early in treatment, nausea, weakness, and nasal congestion.

References

Brusa L, Orlacchio A, Moschella V, Iani C, Bernardi G, Mercuri NB. Treatment of the symptoms of Huntington's disease: preliminary results comparing aripiprazole and tetrabenazine. Mov Disord. 2009 Jan 15;24(1):126-9. doi: 10.1002/mds.22376. PubMed abstract

Tarsy D, Baldessarini RJ, Tarazi FI. Effects of newer antipsychotics on extrapyramidal function. CNS Drugs. 2002;16(1):23-45. PubMed abstract

Miyasaki JM, Shannon K, Voon V, Ravina B, Kleiner-Fisman G, Anderson K, Shulman LM, Gronseth G, Weiner WJ; Quality Standards Subcommittee of the American Academy of Neurology. Practice Parameter: evaluation and treatment of depression, psychosis, and dementia in Parkinson disease (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2006 Apr 11;66(7):996-1002. PubMed abstract