• S L Jansen, D A Forbes, V Duncan, and D G Morgan.
• Cochrane Db Syst Rev. 2006 Jan 25 (1): CD003802.

BackgroundThere are a number of studies that suggest a relationship between decline of melatonin function and the symptoms of dementia.ObjectivesThe review assessed the evidence of clinical efficacy and safety of melatonin in the treatment of manifestations of dementia or cognitive impairment (CI).Search StrategyThe Cochrane Dementia and Cognitive Improvement Group's Specialized Register was searched for trials involving melatonin on 5 October 2005. The search terms used were MELATONIN, and N-ACETYL-5-METHOXYTRYPTAMINE. This Register contains records from all major health care databases as well as many ongoing trials databases and is updated regularly.Selection CriteriaAll relevant, randomized controlled trials in which orally administered melatonin in any dosage was compared with a control group for the effect on managing cognitive, behavioural (excluding sleep), and/or affective disturbances of people with dementia of any degree of severity.Data Collection And AnalysisTwo to three reviewers independently assessed the retrieved articles for relevance and methodological quality, and extracted data from the selected studies. Statistically significant differences in changes in outcomes from baseline to end of treatment between the melatonin and control groups were examined. Each study was summarized using a measure of effect (e.g. mean difference) and meta-analyses were conducted when appropriate.Main ResultsThree studies met the inclusion criteria. This review revealed non-significant effects from the pooled estimates of MMSE cognitive, and ADAS-cognitive change scores. Individual study estimates for treatment effect demonstrated a significant improvement for melatonin compared with placebo in behavioural and affective symptoms as measured by the ADAS non-cognitive scale in a study of 20 patients, and the Neuropsychiatric Inventory (NPI) following treatment with 2.5 mg/day (SR) melatonin, but not with 10mg/day (IR) melatonin in a larger study of 157 patients. The remainder of the treatment effects for affect, behaviour and activities of daily living were non-significant.Authors' ConclusionsThere is insufficient evidence to support the effectiveness of melatonin in managing the cognitive and non-cognitive sequelae of dementia.

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