Melatonin decreases delirium in elderly patients: a randomized, placebo-controlled trial

Disturbance in the metabolism of tryptophan and tryptophan-derived compounds (e.g., melatonin) may have a role in the pathogenesis of delirium.

To evaluate the efficacy of low dose exogenous melatonin in decreasing delirium.

A randomized, double-blinded, placebo-controlled study.

An Internal Medicine service in a tertiary care centre in London, Ontario, Canada.

145 individuals aged 65 years or over admitted through the emergency department to a medical unit in a tertiary care hospital.

Patients were randomized to receive either 0.5 mg of melatonin or placebo every night for 14 days or until discharge.

The primary outcome was the occurrence of delirium as determined by Confusion Assessment Method (CAM) criteria.

Of a total of 145 individuals (mean age (standard deviation): 84.5 (6.1) years) 72 were randomly assigned to the melatonin group and 73 to the placebo group. Melatonin was associated with a lower risk of delirium (12.0% vs. 31.0%, p = 0.014), with an odds ratio (OR), adjusted for dementia and co-morbidities of 0.19 (95% confidence intervals (CI): 0.06-0.62). Results were not different when patients with prevalent delirium were excluded.

An intention to treat analysis was not possible due to loss to follow-up.

Exogenous low dose melatonin administered nightly to elderly patients admitted to acute care may represent a potential protective agent against delirium.