Olanzapineにより衝動性亢進が改善したHuntington病の1例

Successful Use of Olanzapine in the Treatment of Severe Impulsive Behavior in Huntington' s Disease

はじめに

　Huntington病(HD)は1872年にHuntington Gにより初めて報告された，常染色体優性遺伝の形式をとり，主として線条体の神経細胞が脱落する変性疾患である。臨床的には，慢性進行性の舞踏様の不随意運動と人格変化や認知機能障害などの精神症状を呈する。

　今回我々は，幻覚妄想状態で衝動性の亢進を来したHDの症例を経験したが，olanzapine投与により精神症状の著明な改善が認められたので文献的考察を交えて報告する。なお，報告にあたっては，口頭にて本人と家族から同意を得た。また，科学的考察に支障のない範囲で，プライバシー保護のために症例の内容を変更した。

　Huntington's disease (HD), which results from a mutation in chromosome 4, is marked by a decrease in the neurotransmitter (GABA, substance P, etc) level in the basal ganglia. Clinically, it is characterized by a triad of motor, cognitive, and psychiatric disturbances. Antipsychotic drugs, especially dopamine antagonists, have been shown to be effective in the control of these symptoms；however, their use is limited by the occurence of adverse effects that are characterized mainly by extrapyramidal symptoms.

　Here, we report the case of a 42-year-old woman with HD who presented with severe impulsive behavior, hallucinations, and delusions, in addition to severe chorea. After admission, we administered haloperidol (3mg/day)；this led to an improvement in the psychomotor excitation. Three weeks after admission, she presented again with aggravated impulsive, hallucinations, and delusions. Her symptoms were alleviated by olanzapine (20mg/day) therapy. Eight weeks after admission, she was discharged from the hospital, and the symptoms have not recurred during the 1-year follow-up period. Therefore, we concluded that olanzapine appears to be useful in the teratment of psychiatric symptoms of HD.