World's largest research project brings together studies of centenarians and near-centenarians to look at global prevalence of dementia in the exceptionally old.
Research led by the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney has addressed the issue of limited understanding of the prevalence of dementia in centenarians and near-centenarians (aged 95+) and whether the risk of dementia continues to rise beyond 100.
The world-first study obtained and harmonised data of 4,427 people aged 95 and above from 18 studies that are part of the International Centenarian Consortium-Dementia, spanning 11 different countries.
The population of people aged 100 - set to reach 2.2 million people within 30 years - has increased dramatically over the last few decades. Policy makers have concerns about the potential impact of this exceptionally ageing population, particularly around increased rates of disease and disability burden upon health and social systems.
According to Yvonne Leung, lead author on the research, an important concern is the increasing risk of dementia with age, with some questioning whether dementia is inevitable for those that live to an extreme old age.
"This is the first and largest study to bring together numerous groups of centenarians and near-centenarians to examine the global prevalence of dementia, and cognitive and functional impairments using a uniform set of diagnostic criteria.
Our primary aim was to obtain a better estimate of dementia prevalence in the very old population from around the world and explore risk and protective factors for dementia that are robust across ethno-regional groups.
Yvonne Leung
The findings, published in Alzheimers & Dementia: The Journal of the Alzheimer's Association indicated that among the exceptionally old, dementia prevalence was 53.2% in women and 45.5% in men, and remains higher in the older participants.
Co-Director of CHeBA and senior author on the paper, Professor Perminder Sachdev, said, "prevalence of dementia, cognitive and functional impairments increased with age without any indication of levelling off after the age of 100.
"We also found that education was protective against dementia, which was similar to previous findings with the younger old.
"However, unlike the findings from the younger old, dementia was not associated with diabetes, vision and hearing impairments, smoking and body-mass index.
We believe that this ethno-regional diverse dataset and its initial findings will facilitate future projects on understanding exceptional longevity and offer important insights into successful ageing.
Professor Perminder Sachdev
