[Huntington's disease presenting with schizophreniform psychosis and narcolepsy in the premotor phase].

The authors report the case of a patient diagnosed and treated with schizophrenia for nearly 20 years. A rapid change in the neurological status of the patient necessitated a diagnostic revision. The patient's additional medical history included narcolepsy and psoriasis. With a stable maintenance antipsychotic combination regime, one and a half years after the last inpatient treatment for a psychotic relapse, initially mild lower limb hyperkinesis developed. At first, this hyperkinesis was hypothesized to be antipsychotic side effects. The decrease of the antipsychotic daily dose resulted in no improvement of the motor symptoms. On the contrary, the generalization of the hyperkinesis and rapid progression of the motoric status were observed. Therefore, further neurological investigation was initiated. Finally, genetic testing confirmed Huntington's disease. The neuropsychological examination at the time of the diagnosis could not confirm major cognitive impairment, however, alterations in a number of cognitive domains were present. During the follow-up period, and by use of the combination of a low-dose partial dopamine receptor agonist and clozapine, no psychotic relapse was detected. The cognitive status exhibited a mild deterioration compared to baseline. In line with the prognosis of Huntington's disease, the motor symptoms slightly progressed despite the pharmacotherapy. We present our case in the context of a literature review. Orv Hetil. 2025; 166(52): 2064-2072.