Perioperative Research into Memory (PRiMe), Part 2: Adult burns intensive care patients show altered structure and function of the default mode network

Background Long-term cognitive impairment (LTCI) is experienced by up to two thirds of patients discharged from Burns Intensive Care Units (BICU), however little is known about its neurobiological basis. This study investigated if patients previously admitted to BICU showed structural and functional MRI changes of the Default Mode Network (DMN). Methods Fifteen patients previously admitted to BICU with a significant burns injury, and 15 matched volunteers, underwent structural and functional MRI scans. Functional connectivity, fractional anisotropy and cortical thickness of the main DMN subdivisions (anterior DMN (aDMN), posterior DMN (pDMN) and right (rTPJ) and left (lTPJ) temporo-parietal junctions) were compared between patients and volunteers, with differences correlated against cognitive performance. Results Functional connectivity between rTPJ and pDMN (t=2.91, p=0.011) and between rTPJ and lTPJ (t=3.18, p=0.008) was lower in patients compared to volunteers. Functional connectivity between rTPJ and pDMN correlated with cognitive performance (r2=0.33, p<0.001). Mean fractional anisotropy of rTPJ (t=2.70, p=0.008) and lTPJ (T=2.39, p=0.015) was lower in patients but there was no difference in cortical thickness. Conclusions Patients previously admitted to BICU show structural and functional disruption of the DMN. Since functional changes correlate with cognitive performance, this should direct further research into intensive care related cognitive impairment.