Methamphetamine psychosis in which tardive dystonia was successfully treated with clonazepam

Reported herein is a case of methamphetamine psychosis in which tardive dystonia was treated successfully with clonazepam. The patient was a 69-year-old man who had taken methamphetamine habitually for approximately 40 years. Auditory hallucinations had developed 25 years previously, for which haloperidol had been prescribed. Tardive dystonia had developed in December 2005. Haloperidol was withdrawn and risperidone or olanzapine alone had been administered, but neither had improved the dystonic posture. However, when clonazepam was added, a gradual improvement in the dystonic posture became evident. Tardive dystonia is currently treated on a trial-and-error basis. Accumulation of further cases similar to the present one is very important for establishing an effective treatment.