Is There a Connection Between Thyroid Dysfunction and Mental Illness?
Written by Kathy Lynch, PharmD – Women’s International Pharmacy
Endocrine glands, and the hormones they secrete, significantly affect the central nervous system (CNS). Thyroid hormones in particular are crucial to the formation and function of the CNS. The inactive thyroid hormone T4 is secreted by the thyroid gland and transported across the blood-brain barrier, where it is converted into T3, the active thyroid hormone. Adequate thyroid hormone levels are necessary to support both the neurons, which are the structural and functional units of the nervous system, and the glia cells, which connect and support the brain and spinal cord.
Suboptimal thyroid function can lead to mental disorders like anxiety, depression, bipolar disorder, and schizophrenia. Hypothyroidism may contribute to apathy, low energy, impaired memory, and problems with attention span. Hyperthyroidism may also result in mood swings, impatience, irritability, and mental decline in the elderly.
To make matters worse, medications used to treat mental disorders can adversely affect thyroid function. A comprehensive review of the medical literature concluded that some medications used to treat bipolar disorder, schizophrenia, and depression are associated with thyroid function abnormalities. These include lithium, phenothiazines, and tricyclic antidepressants. Patients using these classes of medications should be monitored for thyroid dysfunction. Patients receiving other types of mental illness drug therapies may also need to be monitored.
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- Bou KR, Richa S. Thyroid adverse effects of psychotropic drugs: a review. Clin Neuropharmacol. 2011 Nov-Dec; 34(6): 248-55.