"Shaped like a butterfly she sits within the neck," wrote the poet. The thyroid that was so described is much more than a butterfly. The impact that the thyroid gland has on the developing brain is humongous. Much research has been done in this field. Changes in the activity of the thyroid hormone impair the development of fetal brain and as well as function of the mature brain. Deficiency of the thyroid hormone causes mental retardation and cretinism.
Most adults with thyroid dysfunction will develop mental symptoms. Overactivity as well as underactivity of the gland causes disorders. Causality is more evident in hyperthyroidism (overactivity). Hyperthyroidism is a major cause of psychiatric symptoms. It is however worthy to note that majority of mental patients are euthyroid, i.e. have normal thyroid functionality. Underactivity of the thyroid is called hypothyroidism. Genetic factors contribute to the development of mental disorders in hypothyroidism. They also influence the treatment outcome.
Thyroid function test is perhaps one of the most common laboratory tests performed owing to the multitude of disorders credited to thyroid dysfunction. Recent findings in individual genetic variations have led to a better understanding of the effects that thyroid hormones have on mental health. It has been found that brain-thyroid relationships are less apparent in the adult brain, though important. These are more significant in a developing brain.
To sum up, it would be wise to state that a healthy thyroid is necessary for a healthy mind. Hypothyroidism in pregnancy should be diagnosed and treated at the earliest through routine antenatal checkups. Clinically suspicious cases should be screened with a thyroid function test. National programmes exist to make sure that prevalence of iodine deficiency is kept at a low level. Areas endemic for deficiency are assigned special importance. Healthy iodine levels are important to ensure normal functionality of the thyroid.
Thyroid Disease and Mental Disorders: Cause and Effect or Only comorbidity?
Robertas Bunevièius; Arthur J. Prange Jr- Current Opinion Psychiatry. 2010;23(4):363-368.