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

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.