Among military veterans, loneliness is common and associated with poorer mental and physical health and functioning. Epidemiological studies have revealed bidirectional, longitudinal associations between loneliness and posttraumatic stress disorder (PTSD). Little is known about loneliness among treatment-seeking veterans, how loneliness impacts PTSD symptom change during treatment, and whether loneliness has differential associations with specific PTSD symptom clusters.

Data were derived from the Veterans Outcome Assessment, an annual, repeated-measures (baseline and 3-month follow-up) telephone survey of patients beginning new episodes of mental health care in the Department of Veterans Affairs. Participants were 1,155 veterans (23% women) entering PTSD specialty care. We tested whether baseline loneliness predicted change in total PTSD symptom severity and according to the five-factor Dysphoric Arousal model of PTSD using hierarchical regressions in which we statistically adjusted for demographics and mental health encounters.

Loneliness decreased between baseline and 3-month follow-up (d = 0.39). Baseline loneliness predicted change in PTSD for the dysphoric arousal and negative alterations in cognitions and mood symptom clusters, with lonelier veterans demonstrating more PTSD change between baseline and follow-up. However, lonelier veterans also had more severe PTSD symptoms at both timepoints. This pattern of results held even after accounting for different types of treatment encounters between timepoints.

While lonelier veterans have more severe PTSD symptoms, they also make greater improvements in symptoms salient to interpersonal functioning over time. Assessment of loneliness should be incorporated into PTSD treatment planning and considered as a treatment target that could be addressed to promote recovery.

Exposure to trauma was found to increase later violent behaviours in youth but the underlying psychopathological mechanisms are unclear. This study aimed to test whether posttraumatic stress disorder (PTSD) is related to violent behaviours and whether PTSD symptoms mediate the relationship between the number of trauma experiences and violent behaviours in adolescents.

The present study is based on a nationally representative sample of 9th grade students with 3434 boys (mean age = 15.5 years) and 3194 girls (mean age = 15.5 years) in Switzerland. Lifetime exposure to traumatic events and current PTSD were assessed by the use of the University of California at Los Angeles Posttraumatic Stress Disorder Reaction Index (UCLA-RI). Logistic regression was used to assess associations between PTSD and violent behaviours, and structural equation modelling (SEM) was used to examine the meditation effects of PTSD.

PTSD (boys: OR = 7.9; girls: OR = 5.5) was strongly related to violent behaviours. PTSD symptoms partially mediated the association between trauma exposure and violent behaviours in boys but not in girls. PTSD symptoms of dysphoric arousal were positively related to violent behaviours in both genders. Anxious arousal symptoms were negatively related to violent behaviours in boys but not in girls.

In addition to trauma, posttraumatic stress is related to violent outcomes. However, specific symptom clusters of PTSD seem differently related to violent behaviours and they do not fully explain a trauma-violence link. Specific interventions to improve emotion regulation skills may be useful particularly in boys with elevated PTSD dysphoric arousal in order to break up the cycle of violence.