The heterogeneity within posttraumatic stress disorder (PTSD) has been debated for decades, which not only limits accurate conceptualization but also poses significant challenges for interventions and treatments. One way to better understand this heterogeneity and target personalized interventions is to identify potential subtypes or specifiers of PTSD. Irritability, a common psychological response after trauma exposure, is a diagnostic symptom of PTSD. Irritability is characterized by an increased sensitivity to sensory stimuli and a lowered threshold for experiencing anger. Recently, irritability has been proposed as a transdiagnostic clinical feature manifesting across various psychiatric disorders, including depression, anxiety, and PTSD. However, the number of studies examining the clinical significance of irritability as a unique variable in PTSD remains small. Moreover, most studies evaluating irritability conflate it with other related constructs (e.g., anger, hostility, and aggression), potentially extending the manifestation of irritability or overlooking its independent effect.
In a study described in an article recently published in Psychological Trauma: Theory, Research, Practice, and Policy, Nalan Zhan, Lan Zhang, Mingliang Gong, and Fulei Geng used separate and well-validated scales to measure irritability, anger, hostility, and aggression in 151 community-dwelling adults with probable PTSD to examine clinical correlates of irritability, anger, and aggression in PTSD. In addition, they used latent profile analysis (LPA) to identify potential irritability-related groups. The results showed that irritability was uniformly related to all PTSD subscales, whereas anger, hostility, and aggression were specifically related to some PTSD subscales, even after removing overlapping symptoms. Furthermore, the correlations of irritability, anger, hostility, and aggression with other psychopathology and suicidal behaviors varied. After adjusting for all PTSD subscales, trauma exposure, and demographic variables, the authors found that irritability was associated with almost all psychopathology (including depression, attention-deficit/hyperactivity disorder, psychotic-like experiences, and insomnia) and suicidal behaviors, whereas anger, hostility, and aggression were sparsely related to some psychopathology or suicidal behaviors. These findings emphasized the unique role of irritability as a construct measured by multiple items rather than a single symptom that is overlapped with other related constructs. Through LPA, this study further identified two profiles of PTSD, irritability, and aggression, with the 33.8% of participants making up the high-severity group reporting higher rates of clinical outcomes and suicidal behaviors as compared with the reported rates of the 66.2% of participants in the low-severity group.
This study provides initial evidence that irritability, anger, hostility, and aggression are highly related but distinct constructs in the PTSD population. Individuals with high-severity PTSD, irritability, and aggression had higher rates of a broad spectrum of negative outcomes, from depression to suicidal behaviors. The findings highlight the significance of irritability as a hallmark of PTSD and the need to incorporate it into PTSD subtypes. Furthermore, both irritability and PTSD involve abnormalities in cognitive control, threat processing, and reward systems. Mechanisms of the comorbidity need further clarification. Future researchers can also focus on developing and testing potentially transdiagnostic treatments, such as exposure-based cognitive behavior therapy, for individuals who meet full diagnostic criteria for PTSD and experience impairing irritability.