Occurrence of cognitive impairment and dementia after the age of 60: A population based study from northern Italy

Objective: To evaluate the age, gender and education distribution of both cognitive impairment and dementia in the whole old age range of the elderly ( from 61 years of age and over). Subjects and Methods: The study population consisted of all subjects born in 1930 or before, living in the municipality of Faenza and Granarolo, Italy ( n = 7,930). A two-phase study design was implemented, by using the Mini-Mental State Examination and Global Deterioration Scale as screening instruments. The DSM-III-R diagnostic criteria were used for the clinical diagnosis of dementia. A subject was classified as affected by cognitive impairment, no dementia (CIND) if he/she scored 2 or more standard deviations lower than the corrected mean MMSE score. Results: The prevalences of dementia and CIND were 6.5 per 100 ( 95% CI 5.9 - 7.0) and 5.1 per 100 ( 95% CI 4.6 - 5.6), respectively. The prevalence of CIND was higher than that of dementia in the youngest old groups ( 61 - 74 years), both in men and women, whereas the opposite pattern was present among the older old (75+). In the older age groups, dementia prevalence increased exponentially with age, while CIND prevalence was more stable. There was not a substantial gender difference in CIND prevalence in all ages. Only in the subpopulation of higher educated subjects, women had a higher prevalence of both dementia and CIND than men. Lower educated subjects had a higher prevalence of both dementia and CIND. When compared to higher educated persons, subjects without any schooling had odds ratios of 10.9 ( CI 7.0 - 16.7) and 16.7 ( CI 11.2 - 25.0) for dementia and CIND, respectively. Conclusions: Cognitive impairment is very common in the younger old ages ( under 70 years of age), whereas dementia becomes predominant after 75 years of age. Both conditions are strongly related to the educational level. Copyright (C) 2005 S. Karger AG, Basel.