Does Depression Precede or Follow Executive Dysfunction? Outcomes in Older Primary Care Patients

Objective: The authors sought to test the potentially reciprocal relationships between depression and executive dysfunction in older patients over time. Method: In this prospective 2-year cohort study, the authors enrolled 709 patients age 65 years and older who presented for primary care on selected days and gave informed consent. Of these, 431 and 284 patients completed follow-up interviews at 1 year and 2 years, respectively. The main outcome measures included depression diagnosis, and measures assessing selected components of executive functions: the initiation-perseveration subscale of the Mattis Dementia Rating Scale, Trail Making tests A and B, and D Trails (Trails B time minus Trails A time). Results: No cognitive measure was significantly independently associated with depression diagnosis concurrently or in 1-year lagged outcomes. A diagnosis of depression was independently associated with concurrent poorer Trails B time and with both Trails B and D Trails times in 1-year lagged models. In path analyses testing 2-year competing dynamic models, no baseline executive function measure predicted the score on the Hamilton Depression Rating Scale (HAM-D), but HAM-D score independently predicted poorer Trails B and D Trails times. Overall medical burden also independently predicted both depressive and cognitive outcomes, but cerebrovascular risk factors only predicted Trails B time. Conclusions: Older persons with depression are at risk of subsequent decline in at least some aspects of executive functioning. The study’s findings leave open the possibility that either neurobiological or psychosocial factors play prominent roles in the mechanisms underlying the course of geriatric depression.