Aberrant intra and inter network resting state functional connectivity in thyrotoxicosis.

Thyroid hormones epigenetically play an important role in regularization of neural networks and in neural differentiation during brain development. Purpose of this study was to explore the intra and inter network resting state functional connectivity (rsFC) changes underlying the neurobehavioral symptoms in thyrotoxicosis. To understand the pathophysiological changes, we investigated correlation between functional connectivity and clinical and behavioral measures. 28 freshly diagnosed thyrotoxicosis patients suffering with symptoms such as palpitation, loss of weight, trembling and heat intolerance from days to weeks and 28 healthy controls were recruited for this study. Thyrotoxicosis patients showed significantly decreased functional connectivity in sensorimotor network (SMN), fronto-temporal network (FTN), default mode network (DMN), right fronto-parietal network (RFPN), left fronto-parietal network (LFPN) and salience network (SN). Inter network functional connectivity was significantly reduced between basal ganglia network (BGN) and SMN and increased between SN and FTN in thyrotoxicosis. Cognitive functions such as visual retention, recognition of objects, mental balance and performance on neuropsychological tests such as Bender gestalt test (BGT), Nahar-Benson test (NBT) and Mini Mental State Examination (MMSE) also showed significant decline in thyrotoxicosis patients. The altered intrinsic resting state functional connectivity might underlie these cognitive deficits. The increased functional connectivity between SN and FTN suggests the recruitment of additional neuronal circuitry needed to compensate for the neuropathology in the primary neural network in thyrotoxicosis. This article is protected by copyright. All rights reserved.