Neutropenia in a patient with Very-Late-Onset-Schizophrenia-Like-Psychosis under Risperidone treatment – Case report

Abstract

This case report describes the clinical evolution of a 75-year-old man with no psychiatric history, hospitalized for psychotic anxiety, commentary and imperative auditory hallucinations, and multimodal delusions in the absence of an affective disorder or neurocognitive decline. He was diagnosed with very-late-onset-schizophrenia-like-psychosis after a complex differential diagnosis, including Alzheimer’s dementia with psychotic symptoms, delirium, Lewy-body dementia, and other psychiatric or general medical conditions. The patient received antipsychotic treatment (Risperidone up to 3 mg/day) with favorable clinical outcomes. However, the laboratory tests showed a low neutrophil count three weeks into treatment. The thorough interdisciplinary evaluation concluded that another cause of neutropenia other than the pharmacologic treatment was improbable. Risperidone was then progressively switched to Olanzapine up to 10 mg/day. Neutrophils returned to base levels after a few days. Unfortunately, the clinical course was unfavorable, and since the reoccurrence of psychotic symptoms was debilitating for our patient, the decision to rechallenge Risperidone was made, starting with low doses of 0.5 mg/day and slowly increasing to 2 mg/day. Despite normal neutrophil count and positive clinical results after seven days, neutropenia was noticed again after two weeks. Therefore, because of the patient’s vulnerability and the uncertainty of periodic outpatient assessment of complete blood count, he was discharged on Haloperidol with resolution of psychotic symptoms and without any side effects. This report’s primary purpose is to highlight a challenging differential in an elderly patient while presenting a rare but potentially harmful adverse effect of Risperidone treatment.