The endocrine system is composed of several entities producing different hormones. The Central Nervous System (CNS) consists primarily of the brain and the spinal cord. It contains a variety of cells such as neurons, astrocytes, oligodendrocytes, and microglia. There are approximately 100 billion neurons in the human brain. The functions of the CNS include regulation of homeostasis, integration of information, and coordination of movement. Several hormones have receptors in the CNS and play an important role in the regulation of various functions of the CNS under normal conditions. Abnormalities of the endocrine system, either hormonal excess or hormonal deficiency, can adversely affect the CNS functions and cause neuropsychiatric symptoms. This presentation reviews the impact of several hormones (e.g., thyroid hormones, cortisol, testosterone, estrogen, and progesterone) on the CNS functions under physiological conditions and during hormonal abnormalities. Thyroid hormones play a key role in the development of the CNS during embryogenesis and early infancy. Excess thyroid hormones (hyperthyroidism), mainly due to Graves’ disease or toxic adenoma, is responsible for irritability, nervousness, agitation, tremor, insomnia, anxiety, depression, and psychosis. Deficiency in thyroid hormones (hypothyroidism), due to thyroid dysgenesis, iodine deficiency, autoimmunity, surgery, or radiation therapy, is associated with cognitive impairment, anxiety, depression, and psychosis. Cortisol regulates various brain functions (e.g., cognition, mood, and response to stress). Excess cortisol (hypercortisolism), due to adrenocorticotropic-secreting pituitary adenoma (Cushing’s disease) or adrenal tumor (Cushing’s syndrome), is causing cognitive impairment, anxiety, depression, and psychosis. Cortisol deficiency (adrenal insufficiency), of peripheral or central origin, can induce cognitive impairment, depression, and psychosis. Gonadal hormones influence a wide spectrum of normal neurological functions (e.g., cognition, mood, and behavior). Testosterone deficiency in men (hypogonadism), a hereditary, congenital, or acquired medical condition, is responsible for irritability, low libido, anxiety, and depression. Estrogen deficiency in women (hypogonadism/menopause), a hereditary, congenital, or acquired medical condition, is associated with hot flushes, low libido, sleep and mood disorders, cognitive impairment, and depression. It may also predispose to Alzheimer’s disease and Parkinson’s disease. Progesterone deficiency during the luteal phase of the menstrual cycle is responsible for premenstrual syndrome (irritability, mood swing, anxiety, and depression). The appropriate treatment of the above endocrine dysfunctions can reverse most of the neuropsychiatric manifestations.

Hassan M Heshmati, medical doctor, endocrinologist, has 50 years of experience in clinical research in academia (University-Affiliated Hospitals, Paris, France and Mayo Foundation, Rochester, MN, USA), pharmaceutical/biotech companies (Sanofi, Malvern, PA, USA, Essentialis, Carlsbad, CA, USA, and Gelesis, Boston, MA, USA), and personal company (Endocrinology Metabolism Consulting, LLC, Hassan Heshmati and Valerie Shaw Endocrine Research, Anthem, AZ, USA). His research activity has been related to pituitary tumor, hyperthyroidism, thyroid cancer, osteoporosis, diabetes, and obesity. He has extensive knowledge in the development of anti-obesity products. He is the author of 358 abstracts, articles, book chapters, and book related to endocrinology and metabolism.