It has recently become evident that circulating thyroid antibodies are found in excess among patients suffering from mood disorders. Moreover, a manic episode associated with Hashimoto’s thyroiditis has recently been reported as the first case of bipolar disorder due to Hashimoto’s encephalopathy. We report a case in which Hashimoto’s thyroiditis was suspected to be involved in the deteriorating course of mood disorder and discuss potential pathogenic mechanisms linking thyroid autoimmunity with psychopathology.
A 43-year-old woman, with a history of recurrent depression since the age of 31, developed manic, psychotic, and soft neurological symptoms across the last three years in concomitance with her first diagnosis of Hashimoto’s thyroiditis. The patient underwent a thorough medical and neurological workup. Circulating thyroperoxidase antibodies were highly elevated but thyroid function was adequately maintained with L-thyroxine substitution. EEG was normal and no other signs of current CNS inflammation were evidenced. However, brain magnetic resonance imaging evidenced several non-active lesions in the white matter from both hemispheres, suggestive of a non-specific past vasculitis. Brain single-photon emission computed tomography showed cortical perfusion asymmetry particularly between frontal lobes.
We hypothesize that abnormalities in cortical perfusion might represent a pathogenic link between thyroid autoimmunity and mood disorders, and that the rare cases of severe Hashimoto’s encephalopathy presenting with mood disorder might be only the tip of an iceberg.
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