Background: Previous researches in developed countries have established depression as a risk factor for disability in the elderly, but little has focused on disability as a contributor to depression.
Objective: The present study aims: 1) to describe the 3-month incidences of depression among Thai elders with and without disability and 2) to investigate the prospective relationship between the disability and depression.
Material and Method: A 3-month prospective population-based cohort study of 358 elders (142 severe, 89 moderate 127 mild or non-disabled people), aged 60 years and older and living in rural and urban communities, was conducted. Depression was assessed by Euro-D Thai version at baseline and 3 months follow-up. Disability was assessed by World Health Organization Disability Assessment Schedule (WHODAS-II). Impairment was assessed by a modified version of the Burvill Physical Illness Scale. Logistic regression modeling was used to determine whether impairment and disability were independently associated with the onset of late-life depression.
Results: The 3-month incidences were 5%, 14.29% and 22.61% among the elders with no/mild, moderate and severe disability, respectively. Both severe disability and a high number of impairments were each significantly associated with risk of depression (RR3.25 95%CI 1.29-8.18 and RR2.33 95%CI 1.15-4.73, respectively), independently of age, gender and socioeconomic status.
Conclusion: Disability is one of the main contributors in depression in late-life. Improving community and public facilities and accessing to health services (e.g., medical rehabilitation) for disabled older people may not only help to enhance their quality of life but also help to prevent depression.

Keywords: Aging, Depression, Disability, Cohort study, Thailand