Memantine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, is currently the only drug proposed for the treatment of moderate to severe Alzheimer’s disease.¹ It has been shown to have neuroprotective effects by inhibiting the excitotoxic effect of NMDA glutamate receptors.² Memantine has a tolerability profile similar to placebo.¹ However, the worsening of psychotic symptoms in patients with Lewy body dementia (LBD) treated with memantine has been recently reported.³ We describe three patients with probable Alzheimer’s disease who developed worsening or de novo visual hallucinations and agitation after memantine treatment.

CASE REPORTS

Patient 1 was a 65-year-old woman with a 2-year history of slowly progressive cognitive decline, affecting episodic memory, naming and executive-attentive skills. Functional abilities of daily living were impaired. Physical and neurological examination, routine blood tests and electrocardiogram (ECG) were normal. Magnetic resonance imaging (MRI) of the brain showed a bilateral frontotemporal atrophy. A diagnosis of probable Alzheimer’s disease was made, and she was treated initially with rivastigmine, then 2 years later with donepezil (10 mg/day) for a further 2 years. Because the patient’s Mini Mental State Examination (MMSE) score was 14/30 at 69 years, she was prescribed a combination treatment with memantine. Her other drugs included vitamin E supplements, citalopram and quetiapine for mild agitation. One week after the starting …