The Lancet has featured a study investigating the safety and efficacy of memantine on cognition and function in individuals with Down's syndrome.

The prospective, double-blind trial involved 173 patients (age > 40 years) with karyotypic or clinically diagnosed Down's syndrome, with and without dementia, at four learning disability centres in the UK and Norway. Patients were randomised to receive either memantine (n=88) or placebo (n=85) for 52 weeks. The primary outcome was change in cognition and function, measured with DAMES scores and the adaptive behaviour scale (ABS) parts I and II.  

The researchers reported that both groups declined in cognition and function but the rates did not differ between groups for any outcomes. Additionally, after adjustment for baseline score, there were non-significant differences between groups of −4.1 (95% CI −13.1 to 4.8) in DAMES scores, −8.5 (—20.1 to 3.1) in ABS I scores, and 2.0 (—7.2 to 11.3) in ABS II scores, all in favour of controls. Serious adverse effects were reported in 10 (11%) of 88 participants in the memantine group and 6 (7%) of 85 controls (p=0.33) - 5 participants in the memantine group and four controls died from serious adverse events (p=0.77).

The study concludes that memantine is not an effective treatment option for dementia in patients with Down’s syndrome.