Memantine for the treatment of dementia

The use of cholinesterase inhibitors to correct the cholinergic deficit in patients with mild to moderate Alzheimer's disease (AD) is well established. However, the treatment is only effective in about half of the patients for whom it is prescribed. Vascular dementia may respond, at least to some extent, to these drugs (T Erkinjuntti and colleagues, Lancet 2002; 359: 1283-90). In 2002, the Committee of Proprietary Medicinal Products recommended that memantine-a drug that acts on the glutamatergic system rather than the cholinergic system-be approved by the European Commission for the treatment of moderately severe to severe AD. Clinical trials have shown some effectiveness of memantine in the treatment of vascular dementia, although it has not been approved for use in this disorder.

The results of a study of the effects of memantine on moderate to severe AD have recently been published (B Reisberg and colleagues, N Engl J Med 2003; 348: 1333-41). Reisberg and colleagues treated their patients for 28 weeks, assessed several outcome variables, and found that memantine reduced clinical deterioration without significant adverse effects. This study is important as memantine is the only treatment licensed for patients with more advanced AD. WHERE NEXT? Several questions about the use of memantine as a treatment for AD remain to be answered. How beneficial is memantine treatment in routine clinical practice compared with clinical trials? What is the best way to assess treatment effects? How long do the beneficial effects last? Does memantine have neuroprotective, rather than just symptomatic, effects? In addition, we need to know when to switch from cholinesterase inhibitors to memantine or when to co-prescribe memantine with cholinesterase inhibitors. The efficacy of memantine in vascular dementia also requires further investigation.