Familial coaggregation of major psychiatric disorders and neurodevelopmental disorders among first-degree relatives of individuals with generalized anxiety disorder

Background: Anxiety disorders, major psychiatric disorders (e.g., schizophrenia and major affective disorders), and neurodevelopmental disorders (e.g., autism and attention-deficit/hyperactivity disorder [ADHD]) may cluster together within families. However, whether the first-degree relatives (FDRs) of individuals with generalized anxiety disorder (GAD) are at an elevated risk of neurodevelopmental or major psychiatric disorders remains unknown. Methods: We identified 2,378,190 FDRs of patients with GAD and 9,512,760 birth year–matched and sex-matched controls from Taiwan's National Health Insurance Research Database. Neurodevelopmental disorders, including autism and ADHD, and major psychiatric disorders, including schizophrenia, bipolar disorder, major depressive disorder, obsessive-compulsive disorder, and GAD, were identified. Results: The FDRs—parents, offspring, and siblings—of individuals with GAD were more likely to be diagnosed as having schizophrenia (relative risk: 1.22), bipolar disorder (1.36), major depressive disorder (1.29), autism (1.20), ADHD (1.52), obsessive–compulsive disorder (1.21), and GAD (1.61) than are the FDRs of individuals without GAD. Conclusion: Our findings support the notion of a familial coaggregation between GAD, major psychiatric disorders, and neurodevelopmental disorders. Future studies should elucidate the definitive genetic etiology of this familial coaggregation.