Thyroid function and mental disorders: an insight into the complex interaction

To assess the serum levels of Thyroxine (T4), Triiodothyronine (T3) and the thyroid stimulating hormone (TSH) in patients with depression.

Sixty clinically diagnosed and drug naive depressed patients and an equal number of healthy, age and sex matched control subjects were included in this study. The Ham-D scale was used to classify the degree of depression into the mild, moderate and the severe grades. The biochemical parameters (T3, T4 and TSH) were estimated by using commercially available kits. The data were analyzed by using the SPSS-10 software, one way ANOVA and the χ2 test.

The female depressive (n = 48) cases outnumbered the male depressive cases. The distributions of the patients in the mild, moderate and the severe categories were similar. A significant decline in the T3 level and an elevation in the T4 level were found in the depressive cases as compared to those in the healthy controls. ANOVA with multiple comparisons testing among the patient group showed no significant difference in the TSH level when the depressive cases with various degrees of depression were compared. A total of twelve depressive patients were found to have thyroid abnormalities.

This study therefore observed the presence of thyroid dysfunction among the depressive cases, which is most often characterized as the "Lower Thyroid Syndrome". Thus, the inclusion of the thyroid screening test among the depressive patients may be helpful in the proper management of the cases.