Memantine leading to physical aggression in the treatment of chronic catatonia secondary to schizophrenia: A case report.

Introduction: Memantine is a noncompetitive N-methyl-D-aspartate receptor antagonist approved by the FDA for moderate to severe Alzheimer's dementia. Memantine is also recommended as an off-label treatment in current catatonia clinical guidelines when benzodiazepines alone are inadequate. Case: A 37-year-old male with a history of schizophrenia on psychiatric conservatorship, stimulant use disorder, and traumatic brain injury was stabilized on risperidone 4 mg twice daily, diphenhydramine 50 mg twice daily, divalproex delayed release 500 mg twice daily, and lorazepam 1 mg twice daily for catatonia. Lorazepam was titrated for unresolved chronic catatonic symptoms but was not tolerated beyond 5 mg total per day due to hemodynamic instability. Owing to barriers in initiating clozapine or electroconvulsive therapy, the patient was started on memantine to address residual catatonia symptoms. After the addition of memantine, the patient began to spontaneously speak in multiple languages and engage in discharge planning, but shortly after a dose increase to 15 mg daily also displayed increased aggressive behaviors. The aggression improved after decreasing the dose to 10 mg daily, and the patient was discharged. Conclusions: This case adds to the body of evidence for memantine in catatonia with underlying schizophrenia and, to our knowledge, is the first described case of memantine uncovering aggression during catatonia treatment.