New Estimates Up Dementia Rates in Mid-Income Countries

Incidence of dementia higher using 10/66 diagnostic criteria; increased death for those with dementia

WEDNESDAY, May 23 (HealthDay News) -- Use of 10/66 dementia diagnosis criteria (10/66) results in an increase in the estimated incidence of dementia in middle-income countries, according to a study published online May 23 in The Lancet.

To investigate the incidence of dementia, Martin Prince, M.D., from King's College London, and colleagues conducted a population-based cohort study of 12,887 individuals aged 65 years or older residing in urban sites in Cuba, the Dominican Republic, and Venezuela, and in rural and urban sites in Peru, Mexico, and China. Three to five years after cohort inception, incident dementia was ascertained using 10/66 and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria.

Of the participants interviewed at baseline, the researchers found that 11,718 were free of dementia, 69 percent of whom were reinterviewed. During the resulting 34,718 person-years of follow-up, the incidence for 10/66 dementia was 1.4 to 2.7 times higher than the incidence for DSM-IV dementia, ranging from 18.2 to 30.4 per 1,000 person-years. Compared with those who were dementia-free, the risk of mortality was 1.56 to 5.69 times higher for individuals with dementia at baseline. Based on 10/66 diagnostic criteria, increased incidence of dementia correlated with increased age (hazard ratio [HR], 1.67), and decreased incidence of dementia correlated with male sex (HR, 0.72) and higher education (HR, 0.89); no significant correlation was observed with occupational attainment (HR, 1.04; 95 percent confidence interval, 0.95 to 1.13).

"Our results provide supportive evidence for the cognitive reserve hypothesis, showing that in middle-income countries as in high-income countries, education, literacy, verbal fluency, and motor sequencing confer substantial protection against the onset of dementia," the authors write.

The 10/66 Dementia Research Group works closely with Alzheimer's Disease International, which is partially funded by the pharmaceutical industry.

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