Illiteracy and the incidence of Alzheimer's disease in the Yonchon County survey, Korea.

BACKGROUND

This study aims to establish the incidence rates of Alzheimer's disease (AD) and to understand the relations between illiteracy and AD in the Korean Yonchon survey cohort.

METHODS

A community-based, dementia-free cohort of 966 people aged 65 years and older was followed up for an average of 5.4 +/- 1.60 years to detect incident AD cases using a two-phase procedure. Age-specific incidence rates were calculated using a person-years approach with Poisson distribution confidence intervals. Data were analyzed using the Cox proportional hazards model to find the hazard ratio of illiteracy.

RESULTS

The participating percentage of the survivors was 86.4% and 74 subjects were diagnosed with AD. Incidence rates per 1000 person-years were 20.99 (95% CI 16.48 to 26.35) for AD. The hazard ratio of illiteracy was 1.78 (95% CI 1.08 to 2.93) adjusted for age, sex, educational level. AD developed more rapidly with aging in the illiterate group than in the literate group.

CONCLUSIONS

Illiteracy is associated with a higher risk of AD and the risk increases with age.