People with Down Syndrome develop symptoms of Alzheimer’s Disease 20-30 years before others
21 December 2017
A new multi-centre study, led by researchers from King’s College London and UCL, has found that people with Down Syndrome (DS) develop earlier onset of Alzheimer’s Disease (AD), with an average age of diagnosis between 55 and 56. This is 20 to 30 years earlier than other individuals who are at risk of being diagnosed with AD. It also suggested that individuals with DS may decline faster than other individuals with AD once they are diagnosed.
This is the largest study of AD in people with DS to date, and used data from specialist clinics across the England, including the South London and Maudsley NHS Foundation Trust, to estimate the typical age of AD diagnosis, and factors that may impact on survival rates.
The study was led by Professor Andre Strydom from the Department of Forensic and Neurodevelopmental Science at IoPPN at King’s. Professor Angela Hassiotis, UCL Division of Psychiatry and Camden and Islington Foundation Trust, and Dr Zuzana Walker, also UCL Division of Psychiatry, also contributed to the paper.
Individuals with DS are at increased risk to develop AD as they age, due to having three copies of the APP gene on chromosome 21. After diagnosis, people with DS in the study survived for approximately 3.78 years, and age at death was approximately 60 years. Survival rates in this study of people with DS and AD were much shorter in comparison with an equivalent age group with AD in the general population.
The findings illustrate the young age of AD diagnosis in the DS population, as well as the considerable variation in age at diagnosis between 35 and 74 years. Older age and delayed diagnosis of AD is predictive of shorter survival.
Professor Strydom said, ‘Given that people with Down Syndrome are at an ultra-high risk of developing Alzheimer’s Disease, we need to understand the factors associated with both age of onset and survival in this population.
‘This study provides the best estimates of, and insights into, survival in Alzheimer’s Disease within the Down Syndrome population to date. There should be more focus on treatment trials to prevent or delay Alzheimer’s Disease in people with Down Syndrome, who are often overlooked when new treatments are being considered.
‘The study also suggests there is some truth to the idea that the high risk of Alzheimer-type dementia in Down Syndrome is largely driven by genetic factors. Future work is ongoing to understand these genetic factors.’
This study was funded by the Baily Thomas charitable Fund, with support from The LonDownS consortium which is funded by Wellcome.
· Graph showing distribution of age at dementia diagnosis, Strydom et al.