Evolution of Irritability, Anger, and Aggression after Traumatic Brain Injury: Identifying and Predicting Subgroups.

The current prospective, multi-center, longitudinal cohort study examined how veterans/service members (V/SM) changed in their irritability, anger, and aggression (IAA) scores from admission to discharge in post-acute rehabilitation settings. The goals were to identify trajectory subgroups, and explore if there were different predictors of the subgroups. V/SM (n = 346) from five Veterans Affairs TBI Model Systems Polytrauma Rehabilitation Centers participated. The sample was mostly men (92%) and identified as white (69%), black (13%), and other races (18%). Median age was 28 years, and 78% had sustained a severe TBI. Staff rated IAA at admission and discharge using the Mayo-Portland Adaptability Inventory-4 item#15. Four IAA trajectory subgroups were identified: (1) no IAA at admission or discharge (n = 89, 25.72%), (2) resolved IAA (n = 61, 17.63%), (3) delayed onset IAA (n = 31, 8.96%), and (4) persistent IAA (n = 165, 47.69%). Greater post-traumatic stress disorder (PTSD) symptoms were the only consistent predictor of belonging to all the subgroups who had IAA compared with the no IAA subgroup. We conclude that IAA had different trajectories after a TBI. The majority of V/SM had persistent impairment from IAA, a quarter of the sample had no impairment from IAA, and fewer participants had resolving or worsening IAA. Findings emphasize the importance of educating providers and family of the different ways and times that IAA can manifest after TBI. Timely diagnosis and treatment of PTSD symptoms during and after rehabilitation are critical treatment targets.