Neuropsychological Correlates of PTSD and Depressive Symptom Improvement in Compensatory Cognitive Training for Veterans with a History of Mild Traumatic Brain Injury

Abstract

Introduction: Mild traumatic brain injury (mTBI), depression, and PTSD are highly prevalent in post-9/11 veterans. With the comorbidity of depression and PTSD in post-9/11 veterans with mTBI histories and their role in exacerbating cognitive and emotional dysfunction, interventions addressing cognitive and psychiatric functioning are critical. Compensatory Cognitive Training (CCT) is associated with improvements in prospective memory, attention, and executive functioning and has also yielded small-To-medium treatment effects on PTSD and depressive symptom severity. We sought to examine neuropsychological correlates of PTSD and depressive symptom improvement in veterans with a history of mTBI who received CCT. Materials and Methods: Thirty-seven post-9/11 veterans with mTBI histories and cognitive complaints received 10 weekly 120-minute CCT group sessions. Participants completed a baseline neuropsychological assessment, including tests of premorbid functioning, attention/working memory, processing speed, verbal learning/memory, and executive functioning, and completed psychiatric symptom measures (PTSD and depression) at baseline, post-Treatment, and a 5-week follow-up. Paired samples t-Tests were used to examine statistically significant changes in PTSD (total and symptom cluster scores) and depressive symptom scores over time. Pearson's correlations were calculated between neuropsychological scores and PTSD and depressive symptom change scores at post-Treatment and follow-up. Neuropsychological measures identified as significantly correlated with psychiatric symptom change scores were entered as independent variables in multivariable regression analyses to examine their association with symptom change at post-Treatment and follow-up. Results: Over 50% of CCT participants had clinically meaningful improvement in depressive symptoms (≥17.5% score reduction), and over 20% had clinically meaningful improvement in PTSD symptoms (≥10-point improvement) at post-Treatment and follow-up. Examination of PTSD symptom cluster scores revealed a statistically significant improvement in avoidance/numbing at follow-up. Bivariate correlations indicated that worse baseline performance on Category Fluency was moderately associated with PTSD symptom improvement at post-Treatment. Worse performance on both Category Fluency and Category Switching Accuracy was associated with improvement in depressive symptoms at post-Treatment and follow-up. Worse performance on Trail-Making Number-Letter Switching was also associated with improvement in depressive symptoms at follow-up. Subsequent regression analyses revealed that worse processing speed and worse aspects of executive functioning at baseline were associated with depressive symptom improvement at post-Treatment and follow-up. Conclusions: Worse baseline performances on tests of processing speed and aspects of executive functioning were significantly associated with improvements in PTSD and depressive symptoms during the trial. Our results suggest that cognitive training may bolster skills that are helpful for PTSD and depressive symptom reduction and that those with worse baseline functioning may benefit more from treatment because they have more room to improve.