A Risk-Benefit Assessment of Dementia Medications: Systematic Review of the Evidence

Abstract

There is no cure for dementia, and no treatments exist to halt or reverse the course of the disease. Treatments are aimed at improving cognitive and functional outcomes. Our objective was to review the basis of pharmacological treatments for dementia and to summarize the benefits and risks of dementia treatments. We performed a systematic literature search of MEDLINE through November 2014, for English-language trials and observational studies on treatment of dementia and mild cognitive impairment. Additional references were identified by searching bibliographies of relevant publications. Whenever possible, pooled data from meta-analyses or systematic reviews were obtained. Studies were included for review if they were randomized trials or observational studies on dementia or mild cognitive impairment that evaluated efficacy outcomes or adverse outcomes associated with treatment. Studies were excluded if they evaluated non-FDA approved treatments, or if they evaluated treatment in disorders other than dementia and mild cognitive impairment. The literature search found 540 potentially relevant studies, of which 257 were included in the systematic review. In pooled trial data, cholinesterase inhibitors (ChEIs) produce small improvements in cognitive, functional, and global benefits in patients with mild to moderate Alzheimer's and Lewy body dementia, but the clinical significance of these effects are unclear. There is no significant benefit seen for vascular dementia. The efficacy of ChEI treatment appears to wane over time, with minimal benefit seen after 1 year. There is no evidence for benefit for those with advanced disease or those aged over 85 years. Adverse effects are significantly increased with ChEIs, in a dose-dependent manner. A two- to fivefold increased risk for gastrointestinal, neurological, and cardiovascular side effects is related to cholinergic stimulation, the most serious being weight loss, debility, and syncope. Those aged over 85 years have double the risk of adverse events compared with younger patients. Memantine monotherapy may provide some cognitive benefit for patients with moderate to severe Alzheimer's and vascular dementia, but the benefit is small and may wane over the course of several months. Memantine exhibits no significant benefit in mild dementia or Lewy body dementia or as an add-on treatment with ChEIs. Memantine has a relatively favorable side-effect profile, at least under controlled trial conditions. ChEIs produce small, short-lived improvements in cognitive function in mild to moderate dementia, which may not translate into clinically meaningful effects. Marginal benefits are seen with severe disease, long-term treatment, and advanced age. Cholinergic side effects, including weight loss, debility, and syncope, are clinically significant and could be especially detrimental in the frail elderly population, in which the risks of treatment outweigh the benefits. Memantine monotherapy may have minimal benefits in moderate to severe dementia, balanced by minimal adverse effects.