Prevalence of memory impairment 2000-2015 in Sao Paolo, Brazil

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes in prevalence of cognitive impairment across four waves of the Health, Welfare and Aging survey (SABE) with data collected in Sao Paolo, Brazil, in 2000, 2006, 2010, and 2015.
Method: Mini Mental State Exam (MMSE) scores and covariate values were available for 5,191 respondents (62.4% female) aged 60 to 99 across four waves. Cognitive impairment was defined as having <=12 points on a 19-point abbreviated version of the MMSE. Age group, educational attainment (no formal schooling, primary, secondary, post-secondary), self-reported heart disease, stroke, diabetes, hypertension, and BMI (<18.5, 18.5-24.9, 25-29.9, 30+) were adjusted for.
Result: In more recent waves, prevalence of cognitive impairment was higher for respondents aged 60-64 years (9.0% in 2015 vs. 4.6% in 2000), 65-69 years (9.7% in 2015 vs. 5.8% in 2006) and 70-74 years (13.9% in 2015 vs. 5.8% in 2006).
Between 2015 and 2000, respondents were increasingly more likely to report some formal education (90.8% vs. 75.3%), secondary (17.6% vs. 7.3%) or postsecondary education (11.4% vs. 4.3%). Respondents were increasingly more likely to report hypertension (66.5% vs. 54.2%), diabetes (28.7% vs. 17.8%), and be overweight/obese (74.1% vs. 58.9%).
In age-adjusted logistic regressions, respondents in 2015 were more likely to show cognitive impairment compared to 2000 (OR 1.84, CI 1.20-2.82).
Conclusion: SABE respondents showed higher prevalence of cognitive impairment in 2015 compared to respondents of the same age in earlier waves, but differences disappeared after adjusting for chronic disease burden and educational attainment.