Symptoms of an underactive thyroid gland (hypothyroidism) and depression overlap. It is still poorly known how much these two conditions are actually related.
The biological prerequisites are known that can determine such a relationship. Neurobiological studies have uncovered the mechanisms of action of the hormones of this gland on the brain, which can explain how a lack of them affects mood. In addition, hypothetically, this connection may be determined by the immune processes that underlie autoimmune thyroiditis (a common cause of hypothyroidism).
The cause of hypothyroidism symptoms is a slowdown in metabolism. These include:
- hypersensitivity to cold
- dry skin
- weight gain.
All symptoms of the disease are nonspecific. It can be accurately diagnosed only with the help of a blood test for hormones.
Sources: Mayo, American Thyroid Association.
Previous studies have yielded opposite results. They demonstrated both a very significant association of depression with hypothyroidism (a threefold increase in its risk), and a very weak one. The question of how serious this connection was remained open.
German scientists decided to test how thyroid function is associated with depression, given the shortcomings of previous studies. They conducted a meta-analysis of 25 studies that covered a total of nearly 350,000 people. The connection turned out to be quite “modest”.
The risk of depression in hypothyroidism, according to new data, was 30% higher than average. The risk was highest with the most pronounced hormone deficiency (70% higher). With a subclinical course (without bright manifestations), it was increased by 13%. This connection was evident in women, but hardly manifested in men. The link between autoimmune processes and the risk of depression is weak, according to this study.
The authors write that the risk of depression in hypothyroidism appears to be significantly lower than previously thought. Probably, this connection is mainly manifested in women with a severe course of endocrine disorders.