Causal association of attention-deficit/hyperactivity disorder and autism spectrum disorder with post-Traumatic stress disorder

Background Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are two neurodevelopmental disorders that often result in individuals experiencing traumatic events. However, little is known about the connection between ADHD/ASD and post-Traumatic stress disorder (PTSD). This study aimed to investigate the genetic associations between these disorders. Methods Genetic correlation analysis was used to examine the genetic components shared between ADHD (38 691 cases and 275 986 controls), ASD (18 381 cases and 27 969 controls) and PTSD (23 212 cases and 151 447 controls). Two-sample Mendelian randomization analyses were employed to explore the bidirectional causal relationships between ADHD/ASD and PTSD. Results The results of the genetic correlation analysis revealed significant positive correlations of PTSD with ADHD(r^g= 0.70) and ASD (r^g= 0.34). Furthermore, the Mendelian randomization analysis revealed that genetic liabilities to ADHD [odds ratio (OR)=1.14; 95% confidence interval (CI), 1.06-1.24; P=7.88×10^-4] and ASD (OR=1.04; CI, 1.01-1.08; P=0.014) were associated with an increased risk of developing PTSD later in life. However, no evidence supported that genetic liability to PTSD could elevate the risk of ADHD or ASD. Conclusion The findings of this study supported that ADHD and ASD may increase the risk of PTSD, but not vice versa.