Effect of executive function on mortality in the context of depressive disorder among older primary care patients: The PROSPECT study

OBJECTIVE: Little is known about the influence of executive function on mortality in the presence of a depressive disorder. We examined the influence of executive dysfunction on mortality over a 5-year period, within levels of baseline depressive status (major depression, minor depression, no diagnosis).

METHODS: Longitudinal analysis was carried out in the Prevention of Suicide in Primary Care Elderly: Collaborative Trial (PROSPECT). In all, 1,226 persons were assessed at baseline. Vital status at 5 years was the outcome of interest. Depression severity and remission of depression were assessed by the 24-item Hamilton Depression Rating Scale. Response inhibition, one of the executive functions, was assessed with the Stroop Color-Word test.

RESULTS: After a median follow-up of 52.8 months, 223 of 1,226 (18.2%) participants had died. Patients who met criteria for minor depression in the lowest quartile on the Stroop Color-Word test in comparison with those in the highest three quartiles were more likely to die at 5 years of follow-up, even when controlling for potentially influential covariates (adjusted hazard ratio (HR) = 3.00, 95% confidence interval (CI) [1.46, 6.19]). No effect of was found for persons with major depression (adjusted HR 1.09, 95% CI [0.40, 3.01]).

CONCLUSIONS: Executive dysfunction may increase risk of death among older primary care patients with minor depression. If we are to prepare for the increasing need for mental health services, we must engage primary care practices as partners to improve the rates of early recognition of executive dysfunction and less severe forms of depression.