Forecasting the future of Alzheimer's Disease
Better use of health care resources, identification of biomarkers, education for patients and their families, treatment trials, early intervention – these are among the benefits of learning more about individuals who are at risk of developing dementia or Alzheimer's disease, benefits Dr. Kevin Peters, of Trent University's Psychology Department, is working to realize.
"The key is to identify people early," says Prof. Peters, citing the personal and societal costs of dementia and its related diseases.
In the 1991 Canadian Study of Health and Aging, 250,000 individuals over the age of 65 had dementia; and that number was expected to double by 2021 and triple by 2031.
In a separate study started more than four years ago with the University of British Columbia's Clinic for Alzheimer's Disease and Related Disorders, Prof. Peters was looking to learn more about a group of individuals considered to be at risk of developing dementia, of which the most common form is Alzheimer's disease. Within this group; labeled Cognitively-Impaired-Not-Demented (CIND) – some people got better, some people stayed the same and some people got worse; Prof. Peters wanted to know why.
As part of his Ph.D. dissertation, Prof. Peters studied two large samples of CIND individuals. Using a variety of statistical techniques, he identified the same five subgroups in each sample. Each of the subgroups was characterized by a distinct neuropsychological profile, each with predominant dysfunction:
* verbal
* verbal/visuospatial
* memory/verbal
* memory
* visuospatial
Never before had these profiles been identified in CIND individuals, says Prof. Peters, noting that most researchers focus on predicting decline in individuals with mild memory impairment.
"Not much is being done on those who are going to get better, which is why this is important," he says, adding he was looking to learn more about the differences among individuals identified as CIND.
Prof. Peters examined the outcomes of CIND individuals within each subgroup over periods of two to five years. He learned that those CIND individuals with verbal dysfunction were the most likely to get better. After a five-year period, close to 26 per cent of those individuals were diagnosed as being not cognitively impaired, while 50 per cent remained CIND and 24 per cent developed dementia.
Meanwhile, those CIND individuals with memory/verbal dysfunction and memory dysfunction were the most likely to have developed dementia after the same five-year period. Fifty-five per cent of those with memory/verbal dysfunction and 65 per cent of those with memory dysfunction had developed dementia.
The study, funded in part by doctoral training grants from the Natural Sciences and Engineering Research Council of Canada (NSERC), the Alzheimer Society of Canada and Canadian Institutes of Health Research, is slated to be published in The Clinical Neuropsychologist and the Journal of Clinical and Experimental Neuropsychology.
These outcomes have important implications.
"This kind of information will allow us to offer treatments earlier on and to help patients and their families realize what kind of odds they're facing – 40 per cent of individuals identified as CIND get worse," says Prof. Peters. "In the immediate future, we won't be able to say "yes you will or no you won't (get dementia)," unless we identify some sort of genetic or biological marker like in Huntington's Disease, but at least we can provide more detailed information."
Prof. Peters also sees the outcomes of the study as being useful in resource allocation and suggests that due to lengthy waiting lists, those at greatest risk of developing dementia be monitored more closely and more frequently than those in the lower risk sub-groups. As well, clinical trials could be undertaken to determine whether different treatments are more effective in some subgroups than in others.
The next step in the study will see Prof. Peters further examine why those individuals with verbal dysfunction are most likely to get better and why those with memory dysfunction are most likely to be later diagnosed with dementia. Prof. Peters will be working with Trent's Dr. Gordon Winocur and his colleagues at the Rotman Research Institute located at the Baycrest Centre for Geriatric Care in Toronto to conduct this next set of studies and hopes to eventually include patients from Peterborough.
Posted April 13, 2004
