Higher central set point of thyroid homeostasis in drug-naïve patients affected by first episode schizophrenia.

Aim: To assess central set point of thyroid homeostasis in drug-naïve patients affected by first episode schizophrenia.

Methods: This cross-sectional study was conducted in Xinxiang city, Henan, China. Patients were drug-naïve patients affected by first episode schizophrenia, aged 14-50 years old and admitted to the "Second Affiliated Hospital of Xinxiang Medical University" from January 2018 to December 2018. Controls were healthy individuals who underwent annual health from Xinxiang city, a community population of the same age and time period. The parameters of "central set point of thyroid homeostasis" were measured by "thyroid-stimulating hormone (TSH) index" and "thyroid feedback quantile-based index". The parameters were compared between schizophrenia patients and controls. Linear regression models adjusted by age and sex were used to assess the association of schizophrenia with the parameters.

Results: A total of 235 patients and 121 controls were included in this study. Patients affected by schizophrenia had significantly higher prevalence of hyperthyroxinemia and levels of free T4, "TSH index", and "thyroid feedback quantile-based index" than controls. After adjusting age and sex, schizophrenia was independently associated with the higher level of "TSH index" (adjusted β 0.33, 95 % confidence interval 0.17, 0.49) and "thyroid feedback quantile-based index" (adjusted β 0.21, 95 % confidence interval 0.12, 0.30). The results with age and sex matched patients and controls were similar to those observed in the overall study population.

Conclusion: Higher central set point may be the underlying mechanism of thyroid allostatic load in drug-naïve patients affected first episode schizophrenia.