Depressive intensity, duration, and their associations with cognitive decline: a population-based study in Korea

Area of Science:

• Neuroscience
• Epidemiology
• Gerontology

Background:

• Existing studies overlook depression's duration effect on cognitive decline.
• The depression-cognition link remains understudied in Asian countries amidst rising global cognitive burden.
• Biological cues suggest a link between depression duration and cognitive impairment.

Purpose of the Study:

• To comprehensively assess how depression duration and intensity impact cognitive decline at a population level.
• To investigate the depression-cognition association in an Asian cohort, considering duration and intensity.
• To explore potential biases in cognitive decline estimates when depression duration is ignored.

Main Methods:

• Utilized data from 6406 Korean Longitudinal Study of Aging (KLoSA) participants (2010-2018).
• Categorized depressive intensity (none, mild, major) using CES-D10 and measured duration across consecutive interviews.
• Employed multiple linear and meta-regressions to analyze effects on global cognition (K-MMSE) and subdomains, with stratified analyses by age and sex.

Main Results:

• Each additional year of depression duration decreased global cognitive scores by 0.44 points.
• Major depression decreased scores by an additional 0.82 points compared to mild depression, across durations.
• Older adults experienced greater cognitive decline from major depression than middle-aged adults; longer/more intense depression correlated with greater decline.

Conclusions:

• Both depression duration and intensity significantly contribute to cognitive decline.
• Ignoring depression duration leads to overestimation of its impact on cognitive function.
• Findings are crucial for cognitive health preservation strategies in the Asian region, identifying susceptible populations.