Steroid psychosis in a polyarteritis nodosa patient successfully treated with risperidone: tracking serum brain-derived neurotrophic factor levels longitudinally

There are several reports demonstrating the effectiveness of risperidone in treating steroid psychosis [1,2]. We have also previously demonstrated that risperidone did not change serum brain-derived neurotrophic factor (BDNF) levels in patients with schizophrenia [3]. BDNF is associated with psychiatric diseases such as depression or schizophrenia [1]. In the present case, risperidone rapidly diminished our patient's psychiatric symptoms without severe adverse effects. Corticosteroids suppress BDNF levels in the brain, which leads to atrophy of the hippocampus [4]. To the best of our knowledge, this is the first report showing longitudinal tracking of serum BDNF levels in a case of steroid psychosis in a patient with polyarteritis nodosa (PN).Our patient, a 69-year-old woman, had had a diagnosis of PN for 4 years with no previous psychiatric history. Her major symptoms of PN were hypertension, pleuritis, vasculitis, a raised platelet count, and a high level of C-reactive protein. She did not have positive findings for vasculitis in the brain on MRI or magnetic resonance angiography (MRA). She had been treated with steroid pulse therapy (intravenous administration of methylprednisolone at 45 mg/day) followed by betamethasone at 4 mg/day. After 1 month at this dosage, she had experienced a mixed state that included being more talkative than usual, feeling hyperactive, and excited, crying, feeling depressed, and having rapid mood swings, persecutory delusions, and auditory hallucinations. Her score on the Brief Psychiatric Rating Scale (BPRS) was 33 points. Risperidone was started at 1 mg/day and increased to 2 mg/day, and the dose of betamethasone was continued at the same dose (4 mg/day). Her psychiatric symptoms gradually improved, and she reached remission 3 weeks after the initiation of risperidone treatment. Since she demonstrated mild finger tremor, her dose of risperidone was decreased to 1 mg/day without worsening of her psychiatric symptoms. During her course