Risk of dementia continues to rise in the oldest old: The Monzino 80-plus Study
Background: Most dementia sufferers are eighty years or older, the fastest growing segment of the elderly population in western countries. Because of the small number of persons in this age class usually included in population-based studies, prevalence and incidence estimates fluctuate widely in the oldest old, making it hard to establish whether the risk of dementia (and Alzheimer’s disease) continues to rise also at very igh ages.
Objective: To estimate the prevalence and incidence of dementia (mild+) in a prospective, door-to-door population-based study of all eighty years or older residents in eight municipalities of Varese province, Italy (the Monzino 80-plus Study).
Methods: Among the 2,436 eligible residents, information could be gathered for 2,138 individuals (response rate: 87.8%). Of the 1,085 survivors non-demented at baseline, 995 (91.7%) were re-evaluated after an average follow-up period of 3 years. Diagnosis of dementia was based on DSM-IV criteria.
Results: Mean age of the population at baseline evaluation was 87.5 (SD: 4.8) years and 74.1% were women. Some 32% lived alone and 11.5% in an institution. In the whole population, mean education was 5.1 (2.5) years, mean MMSE score 21.4 (7.6), and mean percentage of dependence on IADL 48.5% (36.9%). Prevalence of dementia standardized on the 2008 Italian population was 22.9% (95% CI: 21.1-24.7) and was higher in women 25.8% (95% CI: 23.7-28.1) than in men 17.1% (95% CI: 14.0-20.5). Prevalence increased with advancing age: 13.5% at 80-84 years, 30.8% at 85-89, 39.5% at 90-94, and 52.8% over 94. The number of person-years of observation was 3,110. The estimated annual incidence of dementia standardized on the 2008 Italian population was 8.6% (95%CI: 7.6-9.7) and was higher in women 9.2% (95% CI: 8.0-10.6) than in men 7.2% (95% CI: 5.5-9.2). Incidence as well rose with increasing age: 6.0% at 80-84 years, 12.4% at 85-89, 13.1% at 90-94, and 20.7% over 94.
Conclusions: Although not exponentially, the overall prevalence and incidence rates of dementia continue to rise also in very old age.
Bob DeMarco is an Alzheimer's caregiver and editor of the Alzheimer's Reading Room. The Alzheimer's Reading Room is the number one website on the Internet for advice and insight into Alzheimer's disease. Bob taught at the University of Georgia, was an executive at Bear Stearns, the CEO of IP Group, and is a mentor. He has written more than 700 articles with more than 18,000 links on the Internet. Bob resides in Delray Beach, FL.