Aripiprazole Effects on Psychosis and Chorea in a Patient With Huntington’s Disease
To the Editor: Huntington’s disease is an autosomal dominant inherited disorder characterized by a triad of motor, cognitive, and psychopathological symptoms (1) . Currently, the only treatment options available for the disease are symptomatic. Aripiprazole is a novel antipsychotic drug that possesses the pharmacological characteristics of a partial agonist of the dopamine D 2 and serotonin 5-HT 1A receptors and antagonist of the 5-HT 2A receptor. We report the use of aripiprazole in the treatment of psychotic symptoms in a patient with Huntington’s disease whose diagnosis was confirmed by DNA analysis.
“Mr. A” was a 47-year-old single man who suffered from frequent falls as a result of an unsteady gait and involuntary movements over the past 4 years. He was diagnosed with Huntington’s disease but refused treatment. Approximately 2 years before his current evaluation, he began to demonstrate impairment in activities of daily living and talking to himself. He also developed irritability, persecutory delusions, and intermittent violent behavior toward his family. Obvious choreiform movements and unsteady gait were noted when the patient was admitted to the acute psychiatric ward. His family history was positive for Huntington’s disease, with an elder brother who was bedridden and a sister who died from the disease. His medical history showed that he had only received irregular treatment with risperidone orally (1–3 mg per day) during a 2-week period. Aripiprazole (10 mg per day) was started and increased to 20 mg per day. Subsequently, his personal hygiene and psychotic symptoms were significantly improved within 2 weeks. His choreiform movement decreased significantly, and his gait became stable, enabling him to walk smoothly without assistance. Before treatment with aripiprazole, his score on the chorea sub-item of the Unified Huntington’s Disease Rating Scale was 18. After treatment, his score decreased to 8.
The pathophysiology of involuntary movements among individuals with Huntington’s disease may be related to the dopamine system (2) , although the genetic defect with aberrant cytosine-adenine-guanine trinucleotide repeats in the ITI5 gene on the short arm of chromosome 4 implicates dysfunction of the glutamate system. Interestingly, in an animal model it has been shown that a dopamine partial agonist could partially restore social withdrawal behavior in hypoglutamatergic mice (3) , which implicates the interaction of dopamine and glutamate systems. Aripiprazole, which has unique dopamine receptor activity compared with other atypical antipsychotics, may similarly have unique effects in treating the psychotic symptoms of Huntington’s disease. Future controlled studies may help provide an understanding of the role of various neuroleptics in the treatment of psychotic symptoms associated with Huntington’s disease.
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