A symptom-level perspective on irritability, PTSD, and depression in children and adults

Background: Although irritability is a prominent clinical manifestation among traumatized populations, its relationships with other psychopathologies are rarely studied. Adopting a symptom-level perspective, this study aimed to explore how symptoms of irritability, posttraumatic stress disorder (PTSD), and depression are associated. Method: The Brief Irritability Test, the PTSD Checklist for DSM-5, and the Patient Health Questionnaire-9 were used to measure irritability, PTSD, and depression, respectively, in a large sample of trauma-exposed children and adolescents (n n = 5454), trauma-exposed adults (n n = 4718), and children and adolescents with probable PTSD (n n = 556). Exploratory graph analysis (EGA) and network analysis were conducted to examine potential communities and significant relations. Results: Although irritability, PTSD, and depression were highly correlated at the disorder level, EGA results indicated that, at the symptom level, they formed highly stable and dense communities, respectively. Relations across disorders mainly emerged at symptoms related to negative cognition, dysphoria, and suicidal thoughts. Especially, strong transdiagnostic relations across all samples were "negative beliefs" and "suicidal thoughts", "numbing" and "suicidal thoughts", "startle" and "moving slowly or restless", "bothering" and "moving slowly or restless". Furthermore, irritability symptoms seem more central than PTSD and depression symptoms, with "snap" being the most central node across all networks, especially in the child and adolescent sample. Conclusion: Irritability, PTSD, and depression are relatively independent constructs when analyzed at the symptom level. Irritability symptoms emerged as core symptoms in trauma-exposed populations. Our findings highlight the importance of independent assessment of irritability in the diagnosis and treatment of PTSD.