Objectives: Experimental and clinical data point to an involvement of the central nervous system in Hashimotos thyroiditis (HT) independent of thyroid dysfunction. The neuropsychological function of patients with HT has not been systematically evaluated yet.
Design: In the present prospective study, neuropsychological testing was performed in 26 euthyroid patients with HT compared to 25 euthyroid patients with hormonal treatment for goitre or after thyroid surgery.
Results: Investigating executive function, cognitive flexibility, attention, figural and verbal memory as well as acoustic working memory with established neuropsychological tests no significant differences between the two groups could be detected. However, comparing the number of patients with conspicuous test results we found significantly more patients with a performance below the cut-off point in the d2 attention test regarding carefulness (GZ-F, HT versus control group: 12 vs 5, P<0.05) and attention (KL, HT versus control group: 12 vs 2, P<0.01) than in the control group. Comparison of the demographic and endocrine data of the HT patients revealed a significantly increased mean value of the anti-thyroid peroxidase antibodies (TPO-Abs) in the group with conspicuous results in the d2 attention test (371.4±187.2 vs 69.3±28.7, P<0.05).
Conclusions: The results of the present study point to subtle cerebral dysfunction in a part of patients with HT even in the euthyroid state. These patients might have an increased risk to develop a neuropsychiatric disease. Disturbances of cerebral thyroid hormone metabolism by the anti-thyroid antibodies or an association with an unknown autoimmune disorder affecting the central nervous system could possibly explain the findings.