Prevalence and rates of progression of amnestic mild cognitive impairment. The Italian Longitudinal Study on Aging

Objective: Mild cognitive impairment (MCI) is, at present, the most widely used term to indicate nondemented aged persons with a mild memory or cognitive impairment that cannot be accounted for any recognized medical or psychiatric condition. In fact, MCI is assumed to be pathology-based and therefore amenable to interventions. MCI may be a prodromal phase of dementia, with estimates of 12% of MCI patients developing dementia in 1 year (1,3), 20% over 3 years, and rates of progression to dementia of 19.9% at 5 years in subjects classified 0.5/uncertain dementia with Clinical Dementia Rating scale. Identification of possible risk factors for conversion of MCI to dementia may be crucial for prevention. In the present study, we estimated the prevalence of MCI in the Italian older population (median follow-up of 3.5 years), the rate of progression of MCI to dementia. Design: Randomized, cohort study with a median period of 3.5-year follow-up. Materials and Methods: The data of this study have been obtained during the first prevalence survey study between March 1992 and June 1993 (prevalence day: March 1st, 1992), and during the 2nd prevalence survey study between September 1995 and October 1996 (prevalence day: September 1st, 1995). A total of 3,411 individuals aged 65-84 years, residing in the community or institutionalised was studied. The criteria for the diagnosis of amnesic MCI included: 1) the presence of subjective evidence of memory impairment (assessed with the item 14 of the Geriatric Depression Scale); 2) an objective and clinically significant memory impairment (evaluated with the Babcock Story Recall Test; 3) absence of a clinical dementia (Mini-mental State Examination >24), 4) intact activities of daily living (none Activities of Daily Living Impaired). Results: Prevalence was 1.7% (57 subjects) for amnesic MCI, increased with age and was higher in women. The rate of progression to dementia was 5.9% at 3.5 years. Conclusion: In conclusion, our estimated prevalence of amnesic MCI and our percentage of MCI subjects which progress to dementia was in according to other estimates coming from other large population-based studies with focus on older persons.