Korean Journal of Biological Psychiatry

Objectives : Thyroid hormone deficiency during the neurodevelopmental period can impair brain development and induce psychiatric symptoms. This study examined the association between thyroid dysfunction and the severity of symptoms in schizophrenia patients, and the treatment response of patients with schizophrenia.

Methods : Three hundred thirty-eight schizophrenia patients, with no prior history of thyroid disease or taking medication associated with it, were studied. We assessed the blood thyroid hormone level, the Brief Psychiatric Rating Scale (BPRS) scores on the day of admission and discharge, admission period, dose of administered antipsychotics, and the number of antipsychotic combinations. The collected data were subsequently analyzed using the Kruskal-Wallis test and Pearson's chi-square test.

Results : The percentage of schizophrenia patients who presented with abnormal thyroid hormone level was 24.6%. High total triiodothyronine (TT3) (p = 0.003), low TT3 (p = 0.001), and high free thyroxine (fT4) (p < 0.001) groups showed a higher BPRS score on admission than did the normal thyroid hormone group, while thyroid stimulating hormone (TSH) levels were not significantly correlated with the severity of symptoms. Furthermore, thyroid hormone was not associated with the treatment response assessed by the rate of BPRS score reduction, admission days, use of clozapine, and dose of antipsychotics.

Conclusions : The TT3 and fT4 hormone levels were significantly associated with the severity of symptoms in schizophrenia patients. These relations suggested that thyroid dysfunction may be associated with the severity of schizophrenia. And hence, further analysis of the results of the thyroid function test, which is commonly used in cases of psychiatric admission, is required.

Keywords Thyroid hormones;Schizophrenia;Brief psychiatric rating scale;Antipsychotics.