Treatment of Psychosis and Agitation in Alzheimer's Disease

Symptoms of psychosis or agitation are common in Alzheimer's disease. These symptoms are associated with distress for the patient, an increased burden for caregivers, more rapid cognitive decline, greater risk of institutionalization and mortality, and increased health care costs. In a recent meta-analysis, caregiver education and behavior modification studies revealed a small to medium effect size in treating agitation in these patients. However, none of these studies were double-blind (difficult to achieve in such studies) and none had a control group that received the same amount of staff time as the intervention group, thereby biasing the results toward the active intervention. Among the psychotropic medications that have been studied, only antipsychotics have shown superiority over placebo for the treatment of psychosis and agitation in patients with dementia. However, most studies show only moderate superiority for antipsychotic over placebo and a few studies have been negative. The side effects of antipsychotic medications include sedation, extrapyramidal signs, tardive dyskinesia, weight gain, and the metabolic syndrome. A pooled analysis from 17 short-term trials showed that the mortality rate in patients with dementia receiving antipsychotic medications was 1.6 to 1.7 times as high (60-70% increase in mortality rate) as the mortality rate in patients receiving placebo. These findings led the FDA to issue a black-box warning for antipsychotic medication use in patients with dementia; a more recent meta-analysis reported a slightly lower odds ratio of 1.54 (54% increase in mortality rate). Lithium has several different actions from anticonvulsants, though both are effective in bipolar disorder, especially mania. Lithium is not being proposed here to treat mania in AD though the investigators will monitor symptoms on the Young Mania Rating Scale. In patients with AD, lithium has been studied for its putative cognitive enhancing effects. A few reports suggest that chronic lithium use reduces the risk of dementia, but other data show increased dementia risk with lithium use. A placebo-controlled, single-blind lithium trial showed no cognitive effects in patients with AD, but a recent trial of lithium in 45 patients with mild cognitive impairment (MCI, which often leads to clinically diagnosable AD) showed a small advantage for lithium (n=24) over placebo (n=21) in attention and other cognitive domains. None of these studies with lithium were intended to treat psychosis or agitation in AD, and patients with these symptoms typically were excluded in these clinical trials. There has been no systematic placebo-controlled trial of lithium to treat agitation/aggression with or without psychosis in AD even though lithium is a highly effective treatment for mania with psychosis and symptoms of agitation or aggression. Nonetheless, the published studies of lithium to treat cognitive decline in older patients show that low-dose lithium is safe in patients with MCI or AD. Specific Aims and Hypotheses Specific Aim 1. To compare changes in agitation/aggression with or without psychosis in patients with AD who receive 12 weeks of randomized, double-blind treatment with lithium or placebo. Primary Hypothesis. Over these 12 weeks, the agitation/aggression domain score on the Neuropsychiatric Inventory (NPI) will decrease significantly more on lithium than placebo. Secondary Hypothesis. Over these 12 weeks, the proportion of responders on lithium will be significantly greater than the proportion of responders on placebo. Response is defined as a 30% decrease in NPI core score (defined as the sum of domains for agitation/aggression, delusions and hallucinations) plus a CGI Change score of much improved or very much improved (CGI based on these behavioral symptoms only). Exploratory hypothesis. Over these 12 weeks, the psychosis score, measured by the sum of the NPI domain scores for delusions and hallucinations, will decrease significantly more on lithium than placebo. Specific Aim 2. To evaluate the tolerability of low dose lithium by assessing emergent somatic side effects over the course of the 12-week trial on lithium compared to placebo. Specific Aim 3. To explore associations between improvement on lithium (decrease in agitation/aggression and psychosis scores) and serum brain-derived neurotrophic factor (BDNF) levels (baseline, 12 weeks), a SNP in intron 1 of the ACCN1 gene, and variation at the 7q11.2 gene locus, because these indices are associated with lithium response in bipolar disorder. The investigators do not postulate a specific mechanism of action for lithium in the investigators trial, but will evaluate these three potential predictors of lithium response with the aim of improving patient selection for personalized treatment. The investigators will examine BDNF serum levels as a biomarker correlate of lithium treatment by correlating change in BDNF levels with change in NPI agitation/aggression and psychosis scores.