Differential associations of physical job demands with cognitive impairment in Korean workers aged 45 and older: a 14-year longitudinal study using the Korean Longitudinal Study of Aging (KLoSA)

Abstract

Objectives: To investigate the association between subelements of physical job demands and cognitive impairment risk in middle-aged and older workers in Korea.

Design: Longitudinal study using eight waves (2006-2020) of the Korean Longitudinal Study of Aging.

Setting: Nationally representative sample of the Korean population aged 45 years and older.

Participants: 2170 workers aged 45 and older at baseline.

Primary outcome measures: Cognitive function was evaluated using the Korean version of the Mini-Mental State Examination and cognitive impairment was defined as a score below 24.

Results: High physical strength demands were inversely associated with cognitive impairment (OR 0.31, 95% CI 0.14 to 0.68 for 'always' vs 'never' category). Conversely, frequent heavy lifting (OR 2.67, 95% CI 1.36 to 5.26) and bending, kneeling or squatting (OR 1.69, 95% CI 0.82 to 3.47) tasks were associated with increased impairment risk. Dose-response relationships were observed between all physical job demands and cognitive impairment, persisting among those with lower education but not among those with higher education.

Conclusions: Different types of physical job demands have varying relationships with cognitive impairment in middle-aged and older workers. Tasks requiring high physical strength may protect against cognitive impairment while tasks involving heavy lifting and bending, kneeling or squatting may increase the risk. These findings highlight the need for tailored interventions that consider the type of physical job demands and workers' educational levels to mitigate cognitive impairment risks. Further research is needed to explore the underlying mechanisms and validate these findings.

Keywords: aging; cognition; neurophysiology; occupational & industrial medicine; physiology; public health.

Figure 1. Weighted prevalence of cognitive impairment among study participants by physical job demands. (A) physical strength, (B) lifting heavy objects and (C) bending, kneeling or squatting

Figure 2. Combined effects of physical job demands and educational attainment on cognitive impairment. EDU, educational attainment.