Memantine-related psychotic symptoms in a patient with bipolar disorder.

To the Editor: Memantine is an N-methyl-D-aspartate (NMDA) receptor agonist. It was recently approved in Europe and the United States for treating dementia and has been shown to reduce clinical deterioration in moderate-to-severe Alzheimer’s disease and in vascular dementia.1 Although memantine has been reported to be useful for psychotic symptoms (delusions and hallucinations) in patients with Alzheimer’s disease,2,3 a few anecdotal reports have noted that it may conversely cause hallucinations and delusions.4,5 Herein, we report the case of a patient with bipolar disorder and Alzheimer’s disease who developed delusions and auditory hallucinations as a result of memantine therapy. Significant resolution of these symptoms occurred once treatment was discontinued. To our knowledge, this report is the first to describe psychotic symptoms in a patient with bipolar disorder and comorbid Alzheimer’s disease as a result of memantine treatment.