Association between late-onset depression and incident dementia in Chinese older persons

OBJECTIVE. Previous studies have shown that depression is a precursor / prodrome or susceptible state for the development of dementia. This study aimed to examine the relationship between late-onset depression and subsequent cognitive and functional decline in a cohort of non-demented older Chinese persons at their 2-year follow-up and investigate for possible predictors of cognitive decline. METHODS. A total of 81 depressed subjects and 468 non-depressed community controls were recruited. RESULTS. Subjects with late-onset depression showed significantly more incident Clinical Dementia Rating (CDR) scale decline (odds ratio = 3.87, 95% confidence interval = 2.23-6.70) and dementia (odds ratio = 3.44, 95% confidence interval = 1.75-6.77) than those without depression. A higher proportion of depressed CDR 0 subjects had CDR and functional decline than their non-depressed counterparts. Depressed CDR 0.5 subjects had significantly higher rates of functional decline and lower rates of improvement in CDR than their non-depressed counterparts. CONCLUSION. Diagnosis of depression was a robust predictor of incident very mild dementia (i.e. CDR of 0.5) and depression severity was a predictor of progression to dementia from CDR of 0.5. The association between depression and the risk of CDR decline and dementia was observed in non-demented Chinese subjects. Depression was also associated with persistent mild cognitive deficits in CDR 0.5 subjects.