Hyperthyroidism and psychiatric morbidity: evidence from a Danish nationwide register study

Abstract

OBJECTIVE: Thyroid hormones are essential for the normal development of the fetal brain, while hyperthyroidism in adults is associated with mood symptoms and reduced quality of life. In this study, we aimed to investigate the association and temporal relationship between hyperthyroidism and psychiatric morbidity. DESIGN: Register-based nationwide cohort study. METHOD: Data on hyperthyroidism and psychiatric morbidity were obtained by record linkage of the Danish National Patient Registry and the Danish National Prescription Registry. A total of 2631 hyperthyroid individuals were identified and matched 1:4 with non-hyperthyroid controls and followed for a mean duration of 6 years (range 0-13). Logistic and Cox regression models were used to assess the risk of psychiatric morbidity before and after the diagnosis of hyperthyroidism respectively. RESULTS: BEFORE THE DIAGNOSIS OF HYPERTHYROIDISM, SUCH INDIVIDUALS HAD AN INCREASED RISK OF BEING HOSPITALIZED WITH PSYCHIATRIC DIAGNOSES (ODDS RATIO (OR): 1.33; 95% CI: 0.98-1.80) and an increased risk of being treated with antipsychotics (OR: 1.17; 95% CI: 1.00-1.38), antidepressants (OR: 1.13; 95% CI: 1.01-1.27), or anxiolytics (OR: 1.28; 95% CI: 1.16-1.42). After the diagnosis of hyperthyroidism, there was a higher risk of being hospitalized with psychiatric diagnoses (hazard ratio (HR): 1.51; 95% CI: 1.11-2.05) and an increased risk of being treated with antipsychotics (HR: 1.46; 95% CI: 1.20-1.79), antidepressants (HR: 1.54; 95% CI: 1.36-1.74), or anxiolytics (HR: 1.47; 95% CI: 1.27-1.69). CONCLUSIONS: Hyperthyroid individuals have an increased risk of being hospitalized with psychiatric diagnoses and being treated with antipsychotics, antidepressants, and anxiolytics, both before and after the diagnosis of hyperthyroidism.