TG and major depressive disorder: In the Djurovic et al.’s study, 130 Hashimoto’s thyroiditis patients undergoing l-T4 replacement therapy were compared with 111 patients with normal thyroid function, in which the results showed that even if serum thyroid hormone levels returned to normal, the scores of MMSE, TMT-Trail Making Test, phonemic fluency test, and depression in patients undergoing replacement therapy were worsened, and some cognitive functions and emotion impairment were continuously found as well [23].