Anti-glutamate receptor ɛ2 antibodies in psychiatric patients with anti-thyroid autoantibodies--a prevalence study in Japan.

Patients with anti-thyroid antibodies (ATAs) present various kinds of psychiatric conditions. When these psychiatric patients with ATAs (PPATs) show responsiveness to immunotherapy, they are frequently diagnosed with a diffuse progressive type of Hashimoto's encephalopathy (HE). Anti-glutamate receptor ɛ2 subunit (GluRɛ2) antibodies have previously been reported in HE patients. However, it is unclear whether there is any relationship between PPATs, including HE patients, and anti-GluRɛ2 antibodies. We investigated anti-GluRɛ2 antibodies in the serum and cerebrospinal fluid (CSF) of 15 PPATs, and we compared the results with those of 11 patients with neuropsychiatric systemic lupus erythematosus (NPSLE), an anti-glutamate receptor antibody-related disease. We then compared the neuropsychiatric symptoms between the PPATs with and without anti-GluRɛ2 antibodies. The prevalence of anti-GluRɛ2 antibodies was significantly higher in the CSF than in the serum of PPATs (41.7% versus 6.7%; p=0.040). The prevalence of anti-GluRɛ2 antibodies was slightly higher in the CSF of PPATs than NPSLE patients. PPAT-GluR(+)s showed a significantly higher prevalence of emotional instability (100% versus 33.3%; p=0.03) and also showed a significantly lower prevalence of delusions (0% versus 100%; p=0.001) and hallucinations (17% versus 83%; p=0.038) than PPAT-GluR(-)s. Our results suggest that anti-GluRɛ2 antibodies may be associated with the neuropsychiatric manifestation of PPATs.