BIDIRECTIONAL RELATIONSHIP BETWEEN DISABILITY AND COGNITIVE IMPAIRMENT: A LONGITUDINAL STUDY AMONG TAIWANESE OLDER ADULTS

Abstract Background Cognitive impairment and disability are two significant age-related health issues in older adults, but the relationship between each other remains unclear. Several cross-sectional studies have established the associations between cognitive impairment and disability. While the previous longitudinal studies reported inconsistent results. Aims & Objectives We aim to simultaneously explore the relationship between cognitive impairment and disability and further pinpoint which one holds a more pivotal role in the relationship. Method 628 participants aged 66.0 (SD=7.3) were retrieved from the Social Environment and Biomarkers of Aging Study, a nationally representative longitudinal survey of Taiwanese study, conducted in 2000. Cognition was evaluated by using a modified Short Portable Mental Status Questionnaire (SPMSQ), and disability was indicated by Activity of daily living (ADL), Instrumental activity of daily living (IADL), and Mobility. Structural equation models with cross-lagged analysis were performed for path analysis. Results The cross-lagged model was well constructed (χ2 (9)=34.5941, p<0.0001, RMSEA=0.0673, CFI=0.99, SRMR=0.03). Baseline disability in 2000 significantly predicted future cognitive impairment (β=−0.25, p<0.05) in 2006, and baseline cognitive impairment in 2000 also significantly predicted future disability (β=−0.03, p<0.05) 6 years later. Fisher’ s Z test, examining difference of the standardized coefficients from two cross-lagged paths, showed statistically significance(p<0.001). Discussion & Conclusion The findings suggested the relationships between cognition and disability are bidirectional in older adults. Compared to the impact of cognitive function on disability, disability presented a greater influence on subsequent cognitive impairment. The potential mechanisms of such kinds of associations might be complicated. To explain the mechanism, future research, focusing on comorbidities, physical and mental capacities, social interactions, unhealthy lifestyles, and the inflammation process, is warranted.