The relationship between depression and cognition in a population of military patients with traumatic brain injuries: A two-year longitudinal study.

摘要

The mission of the current investigation was as follows. The first aim was to investigate whether differences in cognitive functioning existed between depressed and non-depressed TBI patients. The second objective was to examine the incidence and recovery course of depression in a matched case series (within subjects) group of TBI patients over tune. The third purpose of this study was to evaluate how changes in depression over time impacted the cognitive performance of this TBI population. Nine hundred thirty-five active duty military patients from the branches of the army, navy, air force, marine corps, and also military cadets participated in the present investigation. Subjects (mean age = 28.54, mean years of education = 13.03) were treated as outpatients and inpatients by the Neurology, Neuropsychology, Social Work and Physical Medicine and Rehabilitation departments at Walter Reed Army Medical Center (WRAMC). Data from the subacute (baseline) stage (mean days since initial TBI = 13.67), twelve month and twenty-four month follow-up evaluations were used in the present investigation. There was no significant difference between depressed and non-depressed subjects on most of the cognitive measures. Multiple comparisons analysis determined significant linear and inverse differences between depression scores from baseline to the 12 month follow-up testing session (mean difference = 1.89; p = .001) and from baseline to the 24 month follow-up testing session (mean difference = 2.14; p = .001), suggesting that depression improved over time.; The temporal relationship between cognitive performance and the duration of time since TBI was assessed using linear and inverse curve estimation regression models. The findings suggest that cognitive performance improved over time. Due to a paucity of research in this area, it cannot be definitively concluded that the underlying substrates of depression seen alter mild TBI and those observed in clinical depression are the same (Busch and Alpern, 1998). Perhaps this apparent ‘recovery/improvement’ of cognitive performance is really nothing more than the manifestation of practice effects over time. Also, inconsistencies in the conclusions of different studies may (to some extent) reflect methodological differences such as the following: use of different TBI criteria, employment of samples that combine mild moderate and severe TBIs and variations in the interval between in jury and initial assessment. Clearly, more research is needed that explores the interactive effects of depression and time since injury. Until these pathophysiological and methodological issues are fully examined, caution should be exercised when drawing conclusions as to the effects of depression and time since injury in TBI populations.