Poorer Inhibitory Control Uniquely Contributes to Greater Functional Disability in Post-9/11 Veterans

Abstract

Abstract Objective Post-9/11 Veterans endorse greater self-reported functional disability than 80% of the adult population. Previous studies of trauma-exposed populations have shown that increased post-traumatic stress disorder (PTSD) and depressive symptoms are consistently associated with greater disability. Additionally, poorer cognitive performance in the domain of executive functions, particularly inhibitory control, has been associated with disability, though it is unclear if this effect is independent of and/or interacts with PTSD and depression. Method Three overlapping samples of n = 582, 297, and 183 combat-deployed post-9/11 Veterans completed comprehensive assessments of executive functions, PTSD and depressive symptoms, and self-reported World Health Organization Disability Assessment Schedule-II (WHODAS II). Results Poorer performance on measures of inhibitory control (Delis-Kaplan Executive Functioning System Color-Word Interference-CWI Test and gradual-onset Continuous Performance Test-gradCPT), but not other executive functions, were significantly associated with greater disability on the WHODAS II (ρ’s = −.13 and −.13, p = .002 and .026, respectively). CWI inhibitory control measures accounted for unique variance in disability after controlling for PTSD and depressive symptoms (R2 change = 0.02, p < .001). Further, CWI significantly moderated the effect of depressive symptoms on disability, such that better inhibitory control weakened the relationship between depression and disability. Conclusions Inhibitory control deficits are uniquely associated with increased disability in combat-deployed post-9/11 Veterans, and better inhibitory control abilities may serve as a protective factor for depressive symptoms leading to increased disability. Key Points Question In a trauma-exposed Veteran population, does inhibitory control predict functional disability above and beyond PTSD and depressive symptoms? Findings After controlling for PTSD and depressive symptoms, inhibitory control explained unique variance in self-reported disability. Inhibitory control also showed a moderation effect on depression where greater inhibitory control on the color-word interference test reduced the association between depression and disability symptoms. Importance Inhibitory control represents an important mechanism in understanding and improving daily life functioning in trauma-exposed Veteran populations. Next Steps Future research should further characterize the different aspects of inhibitory control deficits in trauma-exposed populations and focus on enhancing inhibitory control paired with more standard psychological distress treatments.