Abstract
Posttraumatic stress disorder (PTSD) is highly prevalent in children exposed to disasters. Yet, there are several widely discrepant diagnostic models of PTSD (DSM-IV, DSM-5, DSM-5 Preschool, and ICD-11); evidence suggests that these models may diagnose different groups of children (Danzi & La Greca, 2016, 2017; La Greca, Danzi, & Chan, 2017). Genetic biomarkers have been identified as a promising diagnostic tool for identifying risk for PTSD (National Research Action Plan, 2013). A large number of studies have investigated candidate genes in adult samples, but this research has not been extended to children. This project investigated genetic risk for PTSD in children (ages 7-11), with an emphasis on exploring genetic correlates of different models of PTSD. Children (n = 87) exposed to Hurricane Ike provided saliva samples for genotyping and completed questionnaires at 8 and 15 months post-disaster. Study 1 investigated the role of ADCYAP1R1 in increasing sex-specific risk for PTSD. ADCYAP1R1 was associated with PTSD when using DSM-IV or the DSM-5 Preschool criteria; no significant findings emerged when using PTSD symptom severity, DSM-5, or ICD-11 criteria. The study replicated prior findings that the CC genotype increased risk for PTSD in the combined sample and in girls. Interestingly, the CC genotype appeared to reduce vulnerability for PTSD in boys. These findings provide preliminary evidence that ADCYAP1R1 may function differently in prepubescent children compared to adults. Study 2 investigated two genes associated with the dopaminergic system, DRD2 and SLC6A3. DRD2 was associated with PTSD symptom severity, DSM-IV criteria, and the DSM-5 Preschool criteria. SLC6A3 was not associated with PTSD symptom severity, but was associated with DSM-IV criteria for PTSD. Neither polymorphism was associated with DSM-5 or ICD-11 criteria. DRD2 was associated with the Arousal symptom cluster, whereas SLC6A3 was associated with the Re-experiencing symptom cluster. Taken together, these findings provide evidence for all polymorphisms (ADCYAP1R1, DRD2, and SLC6A3) as having a role in increasing risk for PTSD; however, findings for the polymorphisms varied depending on which conceptualization of PTSD was used. Future research will need to take the evolving definitions of PTSD into account in order to better understand the genetic etiology of the disorder.