**2.1 Participants**

Participants enrolled in the RCT and the explorative analysis were recruited from two Dutch mental health centres (Centre'45/Arq and Sinai Centre), which specialized in treating trauma-related disturbances. To capture important age-related challenges and losses in terms of emotional attachment, physical independence and socio-economic setbacks [11], treatment-seeking, community-dwelling out-patients with PTSD aged 55 years and over were accepted for this trial. Participants were enrolled between April 2013 and April 2016. Exclusion criteria involved not meeting full PTSD-IV criteria, changes in psychotropic medication during the study, severe cognitive impairment, high suicide risk, psychosis or bipolar disorder, current substance use disorder and concurrent psychosocial treatment during the study. Half of the sample consisted of native Dutch participants, the other half of resettled refugees from various countries, mainly from the Middle-East. The 33 civilian trauma survivors reported traumatic events including persecution, political, domestic and sexual violence, including childhood abuse. These events took place throughout the life course. The participants' age ranged from 55 to 81 years; a mean age being 63.81 years, SD = 6.8 years; as for the gender distribution, 75% were men. All participants had encountered multiple adverse events. A total of 36.4% of the participants reported childhood trauma, implying Adverse Childhood Events (ACEs) between age 5 to 12; 30.3% reported sexual trauma. The majority (60.6%) of the participants suffered not only from PTSD (DSM-IV; 2000), but additionally from comorbid depression symptoms.
