Hormones and Schizophrenia

There are many complex interrelationships between the endocrine system and the nervous system. Important connections between hormones and mental health have been observed. In this chapter, we briefly explore significant historical aspects of psychoneuroendocrinology and then describe the current classification and physiological systems of the key hormones of the hypothalamus, pituitary, and target organs. The hypothalamic-pituitary-gonadal axis is discussed in some detail, with a focus on the role that estrogen plays in neurotransmitter modulation, particularly in schizophrenia. Next, the role of prolactin, which is a potent dopamine antagonist, is reviewed. Many antipsychotic drugs exert their therapeutic actions by causing hyperprolactinemia; however, there are potential clinical adverse effects with prolonged hyperprolactinemia such as osteoporosis. A section on the hypothalamic-pituitary-adrenal (HPA) axis is included since it is closely regulated by central mechanisms involving the limbic system and hypothalamus, and therefore, it has an important role in people with schizophrenia. A key hormone of the HPA axis is cortisol, and hypercortisolemia may precipitate or exacerbate psychotic symptoms. The thyroid hormones have been studied for many decades, but in more recent times, the relationship of hyperthyroidism to the onset of schizophrenia has increased evidence. In this section, we examine the direct impact of the thyroid axis hormones on the key neurotransmitters implicated in the development of psychosis, namely dopamine, serotonin, and glutamate. We conclude that hormones play a huge role in the development, perpetuation, and prognosis of people with schizophrenia.