By Anne Harding
NEW YORK—About 45% of people with depressive disorders and 30% of those with anxiety also have autoimmune thyroiditis (AIT), according to new findings.
"Autoimmune thyroiditis is present in a high percentage of cases with depression and anxiety, and this is so far not commonly known," Dr. Teja Groemer, a researcher at the University of Erlangen-Nuremberg and resident psychiatrist in Bamberg, Germany, told Reuters Health by phone.
There is mounting evidence that some psychiatric disorders are autoimmune-related, Dr. Groemer and his team note in JAMA Psychiatry, online May 2. The hypothyroid state has been linked to depression, and depressed patients often have thyroid disease, they add, but there is less evidence for a link between anxiety and AIT.
To better understand these relationships, the authors conducted a systematic review of the literature. The 19 studies they included in their meta-analysis - the first of its kind to compare symptoms of anxiety and depression in people with and without AIT - involved more than 36,000 patients.
Depression and anxiety were both significantly more common among patients with AIT, Hashimoto thyroiditis, or subclinical or overt hypothyroidism, with odds ratios of 3.56 and 2.32, respectively. The authors estimated that 45.5% of depressive disorders and 29.8% of anxiety disorders are associated with thyroid disease.
"Assuming that depression and anxiety disorders are illnesses that often appear together with a comorbidity of up to 57.5%, patients with AIT have a high risk of experiencing combined depression and anxiety disorder," they write. "These circumstances further amplify the relevance of our meta-analytic review."
Symptoms of AIT such as tachycardia at night and high blood pressure could promote anxiety, while thyroid disease can also lead to fatigue, a hallmark of depression, Dr. Groemer noted. Patients with AIT and comorbid anxiety and depression can be especially difficult to treat, he added.
"This is really an evil combination of symptoms because patients feel helpless," Dr. Groemer said. "Often they are very irritated and try many different therapies and nothing works."
But finding out that AIT is likely the source of their depression and anxiety, he noted, can be a big relief to patients, who usually do well with treatment, which includes weight-neutral antidepressants, psychotherapy to help with generalized anxiety, and relaxation strategies, along with selenium supplementation.
While in principle endocrinologists and psychiatrists are aware of the association between thyroid disease and depression, he noted, they don't realize how common depression and anxiety are in people with AIT.
"Patients with AIT and no symptoms of depression and anxiety must be aware of the vulnerability to develop psychiatric issues," Dr. Groemer and his team write. "As a consequence, both a screening for psychiatric symptoms is advisable in patients with AIT and a test for AIT is recommended in patients with depression and anxiety disorders."
JAMA Psychiatry 2018.
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