W3. SHARED GENETIC BACKGROUND BETWEEN SPECIFIC ANXIETY DISORDERS AND SLEEP DISORDERS

Background Disrupted sleep is a common problem among patients with anxiety disorders, but the underlying mechanisms are insufficiently understood. We explored the associations between sleep disorders and specific anxiety disorders – generalised anxiety disorder (GAD), panic disorder (PD) and social anxiety disorder (SAD) – to elucidate shared pathophysiological mechanisms. Methods We defined anxiety disorders and sleep disorders primarily based on the ICD codes. All mental and behavioural disorders were excluded from the controls. Leveraging the FinnGen electronic health record data and the genetic data (N ∼ 500,000), we conducted GWAS to examine genetic associations with separate anxiety disorders. In addition, we used linkage disequilibrium score regression to assess the possible shared genetic risk. For causality estimation, two-sample Mendelian randomization (MR) was applied utilising publicly available summary statistics with the FinnGen data. Results In the FinnGen sample, we had 10,626 cases of GAD, 10,517 cases of PD and 4,094 cases of SD. Significant shared genetic risk was observed between anxiety and sleep disorders (P < 1 × 10^-5). Specifically, insomnia showed strong correlations with GAD (rg = 0.79) and PD (rg = 0.72), while the correlation with SAD was lower (rg = 0.61). Moderate correlations were observed with restless legs syndrome (range rg = 0.30–0.43) and sleep apnoea (range rg = 0.20–0.39). MR indicated a causal effect of insomnia on GAD (IVW P = 0.002) and PD (IVW P = 4.6 × 10^-4). Reverse MR was limited by a lack of instrumental variables for specific anxiety disorders. Discussion The substantial shared genetic risk suggests common pathophysiological pathways between insomnia and GAD or PD, which appear less pronounced in SAD. MR evidence for a causal role of insomnia in GAD and PD highlights sleep disturbances as a potential therapeutic target to reduce anxiety symptoms.