Objective: We investigated the frequency of depressive disorders in the elderly with normal cognition (NC), mild cognitive impairment (MCI) and dementia patients living in the community to find out the association between cognitive disorders and depressive disorders in the community dwelling elderly.

Methods: 6,262 baseline study subjects from November 2010 through October 2012 were enrolled based on the Korean longitudinal study on cognitive aging and dementia which is the first nationwide multi-center population based prospective cohort study in Korea. Diagnosis of MCI, dementia, major depressive disorder (MDD), minor depressive disorder (mDD) and subsyndromal depression(SSD) was made by psychiatrists with expertise in dementia based on the appropriate diagnostic criteria.

Results: 4,303 NC, 1,737 MCI, 222 dementia were enrolled. The frequency of MDD, mDD, SSD were highest in dementia and lowest in NC and showed significant difference among three groups. The odds ratio also increased significantly in MCI and dementia compared with NC showing highest odds ratio in dementia.

Conclusion: Our findings propose that MCI and dementia in the community dwelling elderly were significantly ssociated with various types of depressive disorders showing highest association tendency in dementia.