Reduced cortical complexity in patients with thyroid-associated ophthalmopathy.

Psychical and functional disturbances of thyroid-associated ophthalmopathy (TAO) patients are drawing increasingly attention, despite the characterized ophthalmic symptoms. We aimed to investigate the alterations of structural complexity using fractal dimension (FD) analysis in patients with TAO. Thirty-nine TAO patients and 25 healthy controls underwent high-resolution 3.0 T structural brain magnetic resonance imaging (MRI). FD values of brain regions were calculated by Computational Anatomy Toolbox (CAT12) and compared between groups. The associations between clinical variables and FD values were further estimated. We found that TAO patients exhibited significantly decreased FD values in right caudal anterior cingulate cortex, right lingual gyrus, right pars orbitalis and right cuneus cortex (FDR corrected p < 0.05). FD values of right cuneus cortex were positively correlated with visual acuity, and FD values of right caudal anterior cingulate cortex were also positively correlated with cognitive performance. Meanwhile, FD values of right lingual gyrus were found to be negatively correlated with emotional function. Our study indicated disturbed cortical complexity in brain regions corresponding to known functional deficits of vision, emotion and cognition in TAO. FD might be a potential marker for reflecting the underlying neurobiological basis of TAO.