## Title

Depressive symptoms with cognitive dysfunction increase the risk of cognitive impairment: analysis of the Korean Longitudinal Study of Aging (KLoSA), 2006-2018
November 16, 2020
Citation: Int Psychogeriatr. 2020 Nov 16 1-11 [Epub ahead of print]

OBJECTIVES Geriatric depression complicates cognitive health in older adults. This study aims to investigate the impact of depressive symptoms on cognitive impairment in community-dwelling older adults, depending on whether cognitive dysfunction accompanied.
DESIGN A community-based longitudinal cohort study.
SETTING This study analyzed data from the Korean Longitudinal Study of Aging (KLoSA) from 2006 to 2018.
PARTICIPANTS Among 10,254 individuals who were registered in the KLoSA study, a total of 9119 subjects met the criteria, and 4547 subjects were included in the final analysis. The subjects were grouped into 4 categories based on depressive symptoms and cognitive dysfunction at baseline assessment:'normal control'(NC, n = 3341),'depression only'(Dep-only, n = 652),'cognitive dysfunction only'(CD-only, n = 393), and'depression with cognitive dysfunction'(Dep-CD, n = 161).
MEASUREMENTS Cognitive impairment 10 years later was defined as K-MMSE scores below two percentile on demographically adjusted norms.
RESULTS Ten-year survival, that is, not experiencing cognitive impairment, was 80 $$\pm \,$$1% in NC group, 72 $$\pm$$ 2% in Dep-only group, 52 $$\pm$$ 3% in CD-only group, and 44 $$\pm$$ 5% in Dep-CD group. The hazard ratio (HR) of the Dep-only group (HR = 1.18, 95% CI, 0.97-1.43, n.s.) did not differ from that of the NC group, but the HR of the Dep-CD group was significantly higher (HR = 2.85, 95% CI, 2.23-3.66, p<0.001) than the NC group. When the Dep-CD group was compared to the CD-only group, the HR was 1.13 (95% CI, 0.85-1.49, n.s.), which indicates that it did not significantly differ from the CD-only group.
CONCLUSIONS Our findings suggest that depressive symptoms with cognitive dysfunction are associated with a higher risk of cognitive impairment. Furthermore, cognitive dysfunction occurring with depressive symptoms is as much a risk for cognitive impairment as is pure cognitive dysfunction. Thus, healthcare providers should pay close attention to the community-dwelling elderly when depressive symptoms occur with cognitive dysfunction.