20 year study into dementia and Down syndrome in Ireland paints stark picture

31 July 2017

A 20 year longitudinal study on dementia in adults with Down syndrome in Ireland has found very high prevalence rates, significantly earlier onset than in the general population and high risk rates for dementia for people with Down syndrome.

The findings, which were published in the Journal of Intellectual Disability Research have prompted the study’s lead author to call for a range of urgent measures to address the needs of people with Down syndrome, their families, medical professionals and the care system.

The study followed 77 women with Down syndrome over the age of 35 years who were enrolled and screened in 1996 and then assessed for symptoms of dementia on an annual basis until death, with assessments completed in a specialist memory clinic at the Daughters of Charity Disability Support Service.

The key findings included:

  • 97.4% of the women assessed developed dementia over the 20 year period. In the general population, the estimated prevalence rates are 5-7% in people aged 65 years and over
  • The average or mean age of onset of dementia in the Irish study was 55 years, other international studies report a mean age of onset of dementia at 51.3 years.
  • The risk of developing dementia in people with Down syndrome is 23.4% at age 50, 45% by age 55 and 88% by the age of 65.
  • It was previously thought that people with Down syndrome only lived between 3-5 years, on average, after developing dementia. This study found the average length of survival after developing dementia was 7 years, with some people living with dementia for 20 years and increased survival at advanced dementia. This new data has major implications from a care and resource perspective.
  • Almost 80% of people with Down syndrome and dementia will develop new onset epilepsy. The corresponding figure in the general population is only 11%.
  • The findings mirror international prevalence rates for people with Down syndrome, however, this is the first time there has been a comprehensive longitudinal study in Ireland on this and consequently provides crucial data to help shape and inform policy, resource planning, educational and care needs.

Lead author and principal investigator for the Irish Disability Supplement to the Irish Longitudinal Study on Ageing (IDS-TILDA), Professor Mary McCarron has noted that this is not an isolated finding. Between wave 1 and wave 2 of IDS-TILDA, which was only a three year period, there were findings that the incidence of dementia diagnosis doubled for people with Down syndrome. Professor McCarron called on the Government to introduce new measures to ensure that services and care for people with Down syndrome adequately reflect and prepare for the realities that these findings demonstrate.

She has said that despite international recommendations that people with Down syndrome should have a baseline assessment at the age of 35 years, to date in Ireland baseline measurement of functioning is more often an exception than the norm and there is poor knowledge, understanding, or measurement of decline and change. Consequently, many people with Down syndrome are not diagnosed or are not diagnosed until dementia is at a very advanced stage. Professor McCarron believes that longitudinal follow-up will enable change to be better monitored over time improving diagnostic specificity, understanding of disease progression and potentially the response to treatment.

At a recent presentation to an all-party Oireachtas committee on dementia, Professor McCarron highlighted the need for:

  1. Assessment and diagnosis of dementia in persons with Down syndrome, usually at ages where such assessment has not been traditionally considered for the general population.
  2. The greater use of assessment tools which are more appropriate for people with Down syndrome, such as those used in the study. The authors of the study believe that with some training and support, these could easily be included in the range of tools utilised by GPs and other clinicians.
  3. Specialist memory clinics, and regional assessment centres of excellence should be established with trained and experienced staff to complete assessments and to offer advice and support to people with Down syndrome living with dementia, their family members, as well as primary care, ageing and dementia services consultants, hospitals and ID services providers.
  4. A greater number of experts trained specifically to work with this population, as the current structure is not equipped for this problem.
  5. Education programmes for healthcare professionals in order to promote the timely diagnosis of people with early onset dementia, including those with Down syndrome.
  6. Health and social care services to be reorganised and equipped to provide extended appropriate and humane care for this increasingly at risk group in our population, in light of the extended survival rates of those with Down syndrome who develop dementia. Services are not currently equipped to deal with these challenges.
  7. People with Down syndrome to be included in clinical trials for new treatments as they are not usually included in such trials − a high risk population should not be denied access to potential treatments.

Professor McCarron said: “We now have the statistics for Ireland, and clearly radical changes need to be made in order to respond and address the needs of this often vulnerable group of people to help diagnose, support, treat and help prevent dementia.

We need to support people with Down syndrome and dementia to live in the home of their choice with their family or friends for as long as possible.  Supports should include appropriate dementia specific respite services for family and/or peers in group homes.   Clinical support and education should be provided to family and staff caregivers. We need tailored dementia specific day programmes and residential options, as well as care approaches which are stress free and environments which are dementia capable.”

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