A randomized double-blind placebo-controlled trial suggests that memantine — a drug used to slow down Alzheimer disease — is an effective prophylactic treatment for migraine. The trial included 60 patients with migraine without aura, who were randomly allocated to receive memantine or a placebo. Memantine reduced the frequency of attacks per month, and reduced the number of days patients were absent from work, the severity of headache and disability scores. Adverse effects were minimal; three patients who received memantine experienced sedation, mild vertigo and nausea, and drowsiness.