Methylphenidate and Other Pharmacologic Treatments for Apathy in Alzheimer's Disease

Apathy is a common and important yet often ignored neuropsychiatric symptom of Alzheimer's disease (AD). Cholinesterase inhibitors and memantine, used to treat AD, appear ineffective against apathy. A meta-analysis of 4 randomized, placebo-controlled trials (RCTs) found that psychostimulants significantly attenuated apathy ratings in AD. However, the pooled sample size in this meta-analysis was just 156, and one of the trials was a 2-week crossover study with a large effect. A large RCT (n = 200) has now been published. This study found that methylphenidate (MPH; 20 mg/d) was superior to placebo in the attenuation of apathy scores in patients with possible or probable, mild to moderate AD; the advantage was evident by the end of the second month of treatment and remained evident to the end of 6 months. The effect size at 6 months was small (Cohen d = 0.37). In this RCT, disappointingly, MPH was not superior to placebo on secondary outcomes, including informant-rated apathy, dependence, activities of daily living, quality of life, and neurocognitive performance; caregiver burden was not formally studied. Speculatively, the psychosocial intervention provided to all participants in this RCT may have boosted response in the placebo group, thereby attenuating differences in outcomes between the MPH and placebo groups. A reasonable conclusion is that whereas MPH may attenuate the severity of apathy in patients with AD across as long as 6 months, the absence of improvements in measures of dependence, activities of daily living, and quality of life suggest that this effect of MPH on apathy may not be clinically significant. An unanswered question is whether the benefits of MPH may be clinically significant in real world practice settings in which the delivery of behavioral interventions is not feasible.