Abstract

The relationship between thyroid function and mood disorders has been observed for more than 50 years. Thyroid hormones act in the brain genetically modulating proteins associated with the pathophysiology of mood disorders and potentiating the serotonergic and noradrenergic neurotransmission systems. In the treatment of a depressive episode, the normalization of thyroid hormones is essential, and should be performed in all patients with mood symptoms, especially in those with insufficient responses to treatment, which require more stringent hormone levels than recommended for the general population. In euthyroid patients, potentiation with triiodothyronine has been proven, but T4 hos also been used in high doses in resistant cases, in which it is postulated that there might be a state of resistance to thyroid hormones, not reflected in the peripheral hormonal levels evaluated routinely. The enzymes deiodasas, the thyroid hormone receptor, and the thyroid hormone transporter in the blood brain barrier are white to investigate. The objectives of this review are to provide guidance regarding the use of thyroid hormones in patients with mood disorders, an update on the relationship between thyroid hormones and central nervous system, and the interactions between psychoactive drugs and thyroid function.