Despite the increasing evidence for relationships between thyroid dysfunction and neuropsychiatric alterations, the effect of treatment of thyroid disease on various clinical psychiatric outcomes is controversial. The purpose of this study was to investigate the effect of levothyroxine treatment on depressive symptoms in subjects with subclinical hypothyroidism. A randomized double-blind placebo-controlled clinical trial was performed. Sixty subjects (51 females and 9 males) with subclinical hypothyroidism were enrolled. Beck Depression Inventory was completed for all participants at the beginning of the study and 12 weeks after enrollment. The intervention and control groups received levothyroxine and placebo, respectively, for 12 weeks. There were no statistical differences in the total depression score and its subscales between the two groups at the beginning of the study. The Beck Depression Inventory score decreased from 16.79 ± 13.25 to 12.37 ± 10.01 (p value = 0.04) in the intervention group. The change in score was not significant for the control group (13.77 ± 11.71 to 11.86 ± 10.71; p value= 0.16). The affective subscale of Beck Depression Inventory did not change after 12 weeks of treatment with levothyroxine, while somatic subscale remarkably improved in the intervention group (p value = 0.02). This study showed the efficacy of treatment of subclinical hypothyroidism in people with levothyroxine in relation to depressive symptoms.
Keywords: Affective subscale; Beck Depression Inventory; depression; neuropsychiatric alterations; somatic subscale; thyroid dysfunction.