People with Down’s syndrome are more likely to develop dementia than others and one in three will have the illness as early as in their 50s. Despite this high prevalence, there is very little reliable research about drug treatments for this population.

This small randomised controlled trial (funded by the drug company Lundbeck) aimed to assess the safety and efficacy of memantine on cognition and function in individuals with Down’s syndrome.

Memantine is now recommended by NICE as an option for managing moderate Alzheimer’s disease for people who cannot take AChE inhibitors, and as an option for managing severe Alzheimer’s disease.

The prospective trial involved adults from learning disabilities centres in the UK and Norway (aged 40 and over) with Down’s syndrome, some who had dementia and others who did not.

Participants were randomly allocated to one of two treatment groups:

• Memantine for 52 weeks (88 patients)
• Placebo for 52 weeks (85 patients)

The main outcome of interest was a change in cognition and function, which was measured with the DAMES scoring system and the adaptive behaviour scale.

Here’s what they found:

• Both groups declined in cognition and function but rates did not differ between groups for any outcomes
• 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
• 10 (11%) of 88 participants in the memantine group and six (7%) of 85 controls had serious adverse events (p=0·33)
• Five participants in the memantine group and four controls died from serious adverse events (p=0·77)

The authors concluded:

There is a striking absence of evidence about pharmacological treatment of cognitive impairment and dementia in people older than 40 years with Down’s syndrome. Despite promising indications, memantine is not an effective treatment. Therapies that are effective for Alzheimer’s disease are not necessarily effective in this group of patients.

Links

Hanney, M. et al Memantine for dementia in adults older than 40 years with Down’s syndrome (MEADOWS): a randomised, double-blind, placebo-controlled trial. The Lancet, Early Online Publication, 10 January 2012, doi:10.1016/S0140-6736(11)61676-0. [Abstract]

Learning disabilities and dementia. Alzheimer’s Society fact sheet 430, Dec 2011.

Donepezil, galantamine, rivastigmine and memantine for the treatment of Alzheimer’s disease. TA 217. NICE, March 2011.