Thyroid allostasis in drug-free affective disorder patients

AIM

To assess the thyroid allostasis in drug-free patients with affective disorder.

METHODS

Patients with major depressive disorder or bipolar disorder as drug-free, defined as those without psychiatric drugs exposure for at least 4 months before admission, from a tertiary hospital were recruited in this cross-sectional study. The primary outcomes were "structure parameters of thyroid homeostasis", which include "thyroid's secretory capacity" (SPINA-GT), "sum step-up activity of deiodinases" (SPINA-GD), the ratio of total to free thyroxine and "thyroid homeostasis central set point" (TSH index and "thyroid feedback quantile-based index" [TFQI]), calculated by TSH and thyroid hormones measured at admission. A healthy population and non-affective psychiatric disorder (schizophrenia) from the same catchment area were recruited as two comparison groups.

RESULTS

A total of 1263 cases of major depressive disorder, 1619 cases of bipolar disorder, 1186 cases of schizophrenia, and 162 healthy controls were included in the study. Compared to healthy control, GD and ratio of total to free thyroxine were lower in affective disorders. Bipolar with mania episode had higher GT than bipolar with depressive episode and major depressive disorder (median level at 3.70 vs. 3.04 and 3.03, respectively). Compared with healthy control, schizophrenia had higher TSH index and TFQI, but no increase in these parameters in major depressive disorder and bipolar disorder.

CONCLUSION

Affective disorders have a unique profile of thyroid allostasis with impaired step-up deiodinase activity and reduced serum protein binding of thyroid hormones, but no change in thyroid homeostasis central set point. Mania episode may be associated with higher thyroid secretory capacity.

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.