Research reported today at the Alzheimer's Association 2009 International Conference on Alzheimer's Disease (ICAD 2009) says that the number of people with Alzheimer's and dementia continues to rise among the very oldest segments of the population in contradiction of the conventional wisdom.
Previous epidemiological studies have suggested that the number of people with Alzheimer's and dementia begins to level off and perhaps even go down a bit in people age 90 and above, known as the "oldest old." This is the fastest growing segment of the population in western countries.
"The number of people affected by Alzheimer's and dementia is growing at an epidemic pace, and the skyrocketing financial and personal costs will devastate the world's economies and healthcare systems, and far too many families," said William Thies, Ph.D., Chief Medical & Scientific Officer at the Alzheimer's Association. "We must make the fight against Alzheimer's a priority before it's too late."
The research reported at ICAD 2009 includes a study of more than 2,100 individuals age 80 years or older in eight municipalities of Varese province, Italy, and a systematic review and collaborative analysis of studies reporting the prevalence of dementia in Europe.
The Monzino 80-plus Study - Dementia Risk Continues to Rise in the "Oldest Old"Ugo Lucca, head of the Laboratory of Geriatric Neuropsychiatry at the Mario Negri Institute for Pharmacological Research in Milano, Italy, and colleagues conducted a prospective, door-to-door, population-based study of all people age 80 years or older in eight municipalities of Varese province, Italy, roughly 30 kilometers (20 miles) north of Milan (known as the Monzino 80-plus Study). Their goal was to estimate the prevalence (total number with the disease) and incidence (new cases of the disease) of dementia in this population.
The researchers were able to gather information and an initial dementia evaluation for 2,138 individuals. The mean age of the population at that first evaluation was 87.5 years; 74.1% were women. Mean education was 5.1 years, and mean MMSE score was 21.4. After an average follow-up period of three years, of the 1,085 survivors non-demented at baseline, 995 were re-evaluated for dementia.
Prevalence of dementia standardized on the 2008 Italian population was 22.9% and was higher in women (25.8%) than in men (17.1%). Prevalence increased with advancing age:
- 13.5% at 80-84 years
- 30.8% at 85-89
- 39.5% at 90-94
- 52.8% over 94
The estimated annual incidence of dementia standardized on the 2008 Italian population was 8.6% and was higher in women (9.2%) than in men (7.2%). Incidence also rose with increasing age:
- 6.0% at 80-84 years
- 12.4% at 85-89
- 13.1% at 90-94
- 20.7% over 94
"Gathering reliable information on such a large number of the 'oldest old' makes this one of the largest studies investigating dementia in this age segment of the population," Lucca said. "This study's results confirm that Alzheimer's and dementia are very common among the oldest people in society. We believe this strengthens the need to shift more of the focus of clinical research to this segment of the elderly population."
According to the researchers, though the rate of women who developed dementia during the follow-up period was higher than in men in this study, no definite conclusion can be drawn about this difference because the number of men in the oldest ages became very small.
Systematic Review of Dementia in Europe - Higher Prevalence in Female "Oldest Old"The goal of Dr. Emma Reynish, a consultant geriatrician and coordinator of the European Alzheimer's Disease Consortium from the Victoria Hospital, Kirkcaldy, Scotland, UK, and colleagues at the EuroCoDe (European Collaboration on Dementia) project, was to determine the prevalence of dementia in Europe based on up to date research findings and including data from Eastern Europe. They conducted an extensive literature search using Cochrane review methodologies and compiled a database of all European epidemiological studies in the field up to the present date. 194 articles were identified by the review and 26 studies met inclusion criteria to participate with raw data in the collaborative analysis.
According to the researchers, while dementia prevalence rates for all men and for women up to age 85 confirmed previous findings, age-specific prevalence rates were higher than previously documented in the female "oldest old" age groups, rising to over 50% in those over 95 years.
"Our key findings confirmed that age remains as the single most important risk factor for dementia," Reynish said. "Nevertheless, due to the lack of data in the oldest old in previous prevalence studies, the prevalence of dementia of women over the age of 85 had been underreported."