Thyroid Hormones and Oestrogens as Psychotropic Substances

Overview

There is a close association between thyroid disorders and mental disorders. On the one hand it was revealed thatthe therapeutic effect of antidepressants depends on the functional state of the thyroid and that the concurrentadministration of thyroid hormones, in particular triiodothyronine, with antidepressants hastens their therapeuticeffect and suppresses the resistance to them. On the other hand, evidence was provided that antidepressants affectthe hypothalamo-pituitary-thyroid axis (HPT) and that they reduced in particular the serum thyroxin level. Thegreater the decline of thyroxin after an antidepressant, the more effective the antidepressant. It is assumed that theeffect of antidepressants on the HPT axis is due to their interference with noradrenergic and serotoninergic systems.Antidepressants may affect also various stages of biosynthesis of thyroid hormones, deiodases, thyroid peroxidase.They may form complexes with iodine. It is important to take into consideration that antidepressant treatment islong-term treatment and it is thus important while administering thyroid hormones, in particular triiodothyronine,to monitor TSH, by sensitive method to avoid the development of a thyrotoxic effect. In future it will be moreovernecessary to elucidate more closely mechanisms of the effect of thyroid hormones on the human psyche.The possibility to suppress depression by administration of oestrogens is restricted above all to the group ofpremenopausal or postmenopausal women. Oestrogens improve also in healthy postmenopausal women the mood,cognitive capacity, protract the onset of dementia in women with Alzheimer’s disease and moreover suppressosteoporosis and reduce cardiovascular diseases. The mechanism of action of oestrogens as antidepressants is notclear so far.

Key words:
thyroid hormones, oestrogens, depression, fluoxetine