Visual hallucinations treated with the reinitiation of memantine in a patient with Lewy body dementia.

Objective: To report on a patient with Lewy body dementia who developed worsening of hallucinations with memantine withdrawal and significant improvement with reinitiation of the drug.

Case Summary: A 78-year-old man presented to a geriatric psychiatry clinic in March 2011. The patient had experienced gradual memory loss since 2007 and was diagnosed with dementia with Lewy bodies (DLB) in 2009. His medication regimen included donepezil and memantine; his cognitive and functional status appeared stable. Occasional mild visual hallucinations occurred but were not concerning to the patient or his wife. The patient did well to July 2011, when memantine became restricted within the health care institution; memantine was therefore tapered to discontinuation. From July to September 2011, the patient's cognition and function appeared to decline significantly. He also began experiencing severe visual hallucinations daily. Memantine was reinitiated in September 2011 and, within days, the patient was free of hallucinations. By November 2011, his cognition and function were noted to have improved to previous status, and hallucinations were rare.

Discussion: Three small randomized studies and 4 case reports were found addressing the use of memantine for DLB. Both improvement and worsening of hallucinations were noted with memantine use in the case reports, but the studies showed only a small benefit in cognition. However, cognitive and psychiatric symptoms worsened when memantine was discontinued. One study found that Neuropsychiatric-Inventory scores and hallucination scores improved significantly for patients taking memantine.

Conclusions: The literature investigating the use of memantine for the psychiatric symptoms of DLB is limited but there are data noting results similar to what we observed in our patient when his memantine was discontinued and reinitiated.