Depressive symptoms and cognitive function as independent correlates of daily functioning in older adults with cognitive complaints
S. Yoon, S. Y. KimIntroduction
Depression often coexists with cognitive impairment and may act as both a risk factor and a symptom of cognitive decline. Functional loss itself can also trigger depressive symptoms. Prior research shows associations between depressive symptoms and activities of daily living (ADL), though results differ due to varied populations and settings. Since cognition impacts daily functioning, this study examines the independent role of depression and cognition in functional dependence among older adults with cognitive complaints.
Objectives
To investigate whether depressive symptoms predict dependence in basic ADL and instrumental ADL (I-ADL) independently of global cognition. Because >50% scored zero on ADL (independence), analyses excluding these participants were conducted to address ceiling effects.
Methods
Retrospective data from patients with cognitive complaints who completed Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), and ADL/I-ADL assessments were analyzed. Correlation and regression analyses were performed on the full sample and excluding ADL=0 cases (Table 1). Group comparisons examined differences between those with and without basic ADL dependence. Figure 1 shows scatter plots.
Results
MMSE and GDS correlated significantly with ADL and I-ADL, but not with each other. In the full sample (N=69), both depressive symptoms (β=0.333, p<0.001) and cognition (β=–0.355, p=0.002) predicted basic ADL dependence (R²=0.312). However, model assumptions were violated due to many ADL=0 cases. After excluding these (N=32), only depressive symptoms predicted ADL dependence (β=0.486, p=0.004; R²=0.265). For I-ADL (N=69), cognition alone predicted dependence (β=–1.307, p<0.001; R²=0.387). Participants with ADL=0 had higher MMSE scores (19.4±5.0 vs. 14.7±5.4, p=0.001), lower GDS scores (16.4±6.4 vs. 20.3±6.8, p=0.018), and lower I-ADL scores (7.1±4.7 vs. 25.4±10.8, p<0.001) than those with ADL dependence. Age did not differ significantly (p=0.526).
Multivariate regression predicting dependence in ADL and I-ADL Table 1. Long description.