Irritability Among Veterans With Chronic Mild Traumatic Brain Injury: Psychological and Sensory Neurophysiological Factors.

OBJECTIVE: The etiology of irritability among persons with chronic mild traumatic brain injury (mTBI) is poorly understood. The authors investigated relationships among irritability, posttraumatic stress (PTS), and multiple sensory processing indices among veterans with or without mTBI. METHODS: In this cross-sectional study (N=124), military veterans with chronic mTBI (experimental group; N=61) and veterans without a history of TBI (control group; N=63) completed the Brief Irritability Test (BITe; primary outcome) and Irritability Questionnaire (IRQ; secondary outcome). The Posttraumatic Stress Disorder Checklist for DSM-5 was used to measure PTS symptoms, with scores ≥33 indicating probable posttraumatic stress disorder (PTSD). Pain, computerized postural control, and functional hearing (signal-to-noise ratio [SNR] loss) were also assessed. RESULTS: Compared with the control group, the experimental group had significantly greater irritability as indicated by BITe and IRQ scores (Cohen's d=0.75-1.21, p<0.001), higher PTS symptom burden (Cohen's d=0.99, p<0.001), greater pain (Cohen's d=1.00, p<0.001), worse postural control (Cohen's d=0.37-0.65, p≤0.044), and greater SNR loss (Cohen's d=0.51, p=0.005). Probable PTSD (partial eta-squared [η2] effect size=0.27-0.32) and pain (η2=0.05-0.06) correlated with irritability most strongly; mTBI status remained independently associated with BITe scores (η2=0.08) but not with IRQ scores. Greater SNR loss was independently associated with BITe scores (η2=0.04) and marginally associated with IRQ scores (η2=0.028-0.029). CONCLUSIONS: Irritability was a prominent symptom among veterans with chronic mTBI and was strongly associated with PTSD and pain, with additional contributions from auditory processing. These findings suggest that irritability in chronic mTBI is multifactorial, reflecting both psychological and sensory neurophysiological factors.