The relationship between cognitive abilities and depression in the context of old age: Testing for measurement invariance using local structural equation modeling

The negative relationship between cognitive abilities and depression is well-established, but studies that focus on the mental health of individuals with exceptional cognitive abilities specifically report mixed findings. Recent work revealed that measures of mental health might lack measurement invariance across the levels of cognitive abilities, which might explain these discrepancies. The aim of this study was to test the measurement invariance of the Center for Epidemiological Studies – Depression (CES-D) scale across four cognitive abilities: crystallized knowledge, quantitative reasoning, verbal fluency, and working memory. Data from the Health and Retirement Study (HRS) were used. The analyzed sample consisted of 19,475 participants aged 50 years or older. The results showed that CES-D lacked measurement invariance across all four cognitive abilities measured. A prominent pattern emerged, with unstandardized factor loadings and item thresholds decreasing as cognitive abilities increased. This effect seems independent of response scale format but somewhat sensitive to reverse-scored items. The CES-D scores of individuals at different levels of cognitive abilities are not comparable, which may lead not only to incorrect inferences about the relationship between cognitive abilities and CES-D scores but also affect any other research using CES-D where the impact of cognitive abilities on the scales' observed scores is uncontrolled for. The pattern of decreasing item thresholds can also suggest that higher cognitive abilities potentially mask depression symptoms.