**2. Material and methods**

#### **2.1 Subjects**

We conducted a cross-sectional study on VoR and HC in Guangdong Province, People's Republic of China. Subjects living and working in Guangdong who met the criteria of being female, at least 18 years old, right-handed, with an educational attainment above secondary school level were included. Exclusion criteria for VoR and HC were a history of neurological or brain trauma and alcohol or drug use/abuse. Additional exclusion criteria for VoR included a previous or current psychiatric diagnosis other than PTSD, and for HC included any previous or current DSM-IV psychiatric disorder. The Ethics Committee of the Second Xiangya Hospital, Central South University, the People's Republic of China approved the study protocol. Written informed consent was obtained from all subjects in the study. The sample size for this study was projected based on previous research (Lindauer et al., 2004a; Fennema-Notestine et al., 2002; Jatzko et al., 2006a; Abe et al., 2006) where sample sizes ranging from eight to twenty were reported.

VoR subjects: VoR subjects were recruited in two stages. In the first stage, 53 potential subjects were recruited from (a) four public psychological consulting clinics; (b) referred to the clinics by a non-government organization (NGO) specializing in assisting victims of sexual assault; and (c) through advertisements in local newspapers requesting VoR for brain imaging studies. As an incentive for participation, six months free psychological counseling and medical therapy were offered. In the second stage, psychiatrists in the four consulting clinics explained the study to the 53 potential subjects and requested consent to participate in this study. As a result, 23 VoR met the inclusion/exclusion criteria and gave written informed consent.

Healthy Comparison (HC) Subjects: The HC subjects for this study were also recruited through a two-stage process. First, after obtaining the major demographic characteristics (i.e. gender, race, age, height, weight, and educational years) of VoR, we published notices across the province to recruit female health workers with similar demographic characteristics. A total of 65 volunteers agreed to participate and were screened according to inclusion/exclusion criteria. The health status of the HC was determined based on health check reports, as well as an illness history interview conducted by a doctor and a psychiatrist. In the second stage, the exact number of HC was recruited to best match the major demographic characteristics of each case of VoR with PTSD.

In this study, all subjects were measured with the Trauma History Questionnaire (THQ) (Green et al., 1996) and the Posttraumatic Stress Disorder Checklist Civilian Version (PCL-C) (Ruggiero et al., 2003). In addition, two independent, clinically experienced psychiatrists interviewed VoR subjects using the Clinician-Administered PTSD Scale (CAPS) (Blake et al., 1995). The PCL-C was used to predict PTSD diagnoses, and the CAPS was used to differentiate PTSD and non-PTSD VoR subgroups. A senior psychiatrist confirmed the final diagnosis of PTSD.
