P2‐287: Prevalence of Mild Cognitive Impairment (Mci) in Diverse Ethno‐cultural and Geographical Regions Internationally: The Cosmic Collaboration

COSMIC (Cohort Studies of Memory in an International Consortium)1 is a recently established international collaboration of longitudinal epidemiological studies of cognitive ageing. This project proposed to compare the baseline prevalence of MCI across different regions and ethnicities, as represented in studies from Asia, Australia, Europe and North America. The published rates of MCI vary in the participating studies from as low as 3.2% in Pittsburgh, USA, to 34.8% in Sydney, Australia. It was argued that methodological differences may account for some of the discrepancies. A request was sent to all studies for data on demographics, sample representativeness, neuropsychological test performance, functional test scores, memory/cognitive complaints/concerns and criteria used for MCI, with follow up for clarifications. Data from 11 studies were made available, comprising more than 23,000 non-demented individuals aged 60 and older. Uniform diagnostic criteria were applied. The age range in COSMIC was 60-103 years, with males comprising 32.7% to 45.4% in different cohorts of White Caucasian, Hispanic, African Americans and Chinese individuals. Cognitive impairment in the total sample based on harmonised domain scores, using <1.5 SD in any domain as impairment after adjusting for age, sex and education, was 21.0%. Prevalence of MCI (non-standardised) using international consensus criteria was 5.5% for men and 5.8% for women (range 3.2% to 10.8%). MCI prevalence (standardised for sex) increased from 4.5% in 60-69 to 5.8% in 70-90 to 7.1% in 80-89 age group. Sample size >90 years was too small to provide a reliable figure. Amnestic MCI was 1.8% and non-amnestic MCI 3.9% overall. Prevalence of MCI based on CDR = 0.5 was 8.5%, and on MMSE score 24 to 27 (inclusive) was 13.3% overall. Rates of MCI (both aMCI and naMCI) vary with the criteria applied, and harmonisation across studies helps reduce but not eliminate the differences. Factors underlying such differences are worthy of examination. The next step for COSMIC is to examine rates of cognitive decline and incident dementia, and to extend the work to risk and protective factors and biomarkers of dementia in diverse populations. Ref: Sachdev PS, Lipnicki DM, Kochan NA, … COSMIC. COSMIC (Cohort Studies of Memory in an International Consortium): An international consortium to identify risk and protective factors and biomarkers of cognitive ageing and dementia in diverse ethnic and sociocultural groups. BMC Neurol. 2013 Nov 6;13:165.