Jun 19 2006
by Mary J. Shomon, with Dr. William Cline
In a fascinating new study coming out of Greece, researchers have found that depression can be linked to autoimmune thyroid disease. The study findings were published in the March 15 issue of BMC Psychiatry. According to the lead author, Dr. K.N. Fountoulakis, “unipolar depression might be characterized by a ‘low-thyroid function syndrome.’”
This small study involved 60 control subjects and 30 patients experiencing major depression. Among the patients with depression, 20 female and 10 male, and they ranged in age from 21 to 60.
None of the people studied had abnormal TSH levels, or abnormalities in free T3 or free T4 — they would be considered to have no evidence of thyroid disease by many physicians. Yet all of the depressive patients had significantly higher levels of one particular measure of thyroid function, kinown as thyroid binding inhibitory immunoglobulins, than the control subjects. And among the 10 out of 30 patients who had an “atypical” form of depression, all ten were found to have significantly higher levels of thyroid microsomal antibodies — a measure of autoimmune thyroid disease — than the control subjects.
This study found was that there was a relationship between good response to the treatment for depression, and the level of detectably thyroid dysfunction. Those with less thyroid dysfunction had greater likelihood of a good response to treatment for depression. Additionally, In addition, the atypical depressives – those who had significantly higher levels of thyroid microsomal antibodies — were found to be less responsive to treatment than the other people in this study.
Overall, the researchers concluded that the fact that depressed patients in this study had increased Thyroid Binding Inhibitory Immunoglobulins was suggestive of some sort underlying autoimmune process in depression, and that this is independent of the type of depression. Additionally, they found that response to treatment for depression can be predicted on the basis of certain thyroid indicators, with better responses being noted when these indices were closer to normal values.
The authors acknowledge that this study was restricted by the number of patients included as well as by limitations of the methodology employed. They considered their findings exploratory and suggest that additional studies involving more patients need to be conducted to establish what relationships might exist between various types of unipolar depression, thyroid function, and clinical outcome.
What Does This Study Potentially Tell Us?
What this study potentially tells us is there appears be a relationship between the presence of thyroid antibodies and immunological dysfunction in the thyroid that predisposes us, or perhaps even triggers, various forms of depression.
It also reinforces the fact that measure of the thyroid’s immunological factors, including thyroid antibodies, is part of a complete thyroid evaluation, and symptoms cannot be dismissed solely on the basis of normal TSH, T4 and T3 levels.