Determinants of cognitive impairment over time among the elderly in Taiwan: results of the national longitudinal study

This study aimed to identify the risk factors for cognitive impairment among the elderly population in Taiwan. Data were drawn from three waves of the “Survey of Health and Living Status of the Elderly in Taiwan”, a national longitudinal study started in 1989. We included respondents without dementia or cognitive impairment at baseline in 1993 and followed them over a 10-year period. Cognitive function was measured by the nine-item Short Portable Mental Status Questionnaire in 1993, 1999, and 2003. Independent variables, including age, sex, marital status, education, ethnicity, ADLs, IADLs, physical function, social participation, chronic diseases, smoking, and alcohol drinking, were collected at baseline in 1993. Depressive symptoms were assessed by the 10-item Center for Epidemiologic Studies Depression Scale (CES-D). Logistic regression was used to evaluate the predictive factors for cognitive impairment. Of the eligible 1,626 respondents, 72 (4.43%) and 484 (29.77%) individuals did not complete follow-up in 1999 and 2003, respectively, mostly due to death. Our results showed that older age (OR = 2.60, 95% CI = 1.79–3.78), being female, lower educational level, IADL disability (OR = 2.06, 95% CI = 1.38–3.09), and having a history of diabetes (OR = 1.70, 95% CI = 1.06–2.74) or stroke (OR = 2.36, 95% CI = 1.06–5.26) were independent predictors for cognitive impairment in Taiwan.