OBJECTIVE:

To assess the efficacy and safety of Melissa officinalis extract using a fixed dose (60 drops/day) in patients with mild to moderate Alzheimer's disease.

DESIGN:

A four month, parallel group, placebo controlled trial undertaken in three centres in Tehran, Iran.

METHODS:

Patients with mild to moderate Alzheimer's disease aged between 65 and 80 years (n = 42; 18 women, 24 men) with a score of >or= 12 on the cognitive subscale of Alzheimer's disease assessment scale (ADAS-cog) and <or= 2 on the clinical dementia rating (CDR) were randomised to placebo or fixed dose of Melissa officinalis extract. The main efficacy measures were the change in the ADAS-cog and CDR-SB scores compared with baseline. Side effects were systematically recorded.

RESULTS:

At four months, Melissa officinalis extract produced a significantly better outcome on cognitive function than placebo (ADAS-cog: df = 1, F = 6.93, p = 0.01; CDR: df = 1, F = 16.87, p < 0.0001). There were no significant differences in the two groups in terms of observed side effects except agitation, which was more common in the placebo group (p = 0.03).

CONCLUSIONS:

Melissa officinalis extract is of value in the management of mild to moderate Alzheimer's disease and has a positive effect on agitation in such patients.