Dysregulation within the salience network and default mode network in hyperthyroid patients: a follow-up resting-state functional MRI study

This study investigated the aberrant connectivity of the salience network (SN) and default mode network (DMN) and the relevance between these abnormalities and symptom improvement in hyperthyroid patients using resting-state functional magnetic resonance imaging (rs-fMRI). Seed-based functional connectivity (FC) analyses were performed on state fMRI data to reveal possible differences in critical node connectivity in the SN and DMN between 41 new-onset, untreated hyperthyroid patients and 41 healthy controls. Subsequently, follow-up data were available for 25 patients treated with methimazole for one month. Compared with the healthy controls, the patients exhibited abnormal internetwork FC from the SN to the DMN and the executive control network (ECN) and decreased intra-network FC within the SN. Relative to the hyperthyroid state, the antithyroid therapy induced reversible connectivity of the left insula to the dorsal anterior cingulate cortex(dACC)and ECN, and persistently increased connectivity between the SN and DMN in patients with improved thyroid function. Finally, Pearson's correlation analyses were performed among the abnormal FC, neuropsychological assessment and serum free triiodothyronine(FT3)level data. The results indicated that aberrant intra- and internetwork FC in the SN and DMN might underlie the pathogenesis of hyperthyroidism, and antithyroid treatment could regulate the FC of certain key brain regions within the SN and DMN in hyperthyroid patients.