Cognitive Slowing in Gulf War Illness Predicts Executive Network Hyperconnectivity: Study in a Population-Representative Sample

• Main Authors: Monroe P. Turner, Nicholas A. Hubbard, Lyndahl M. Himes, Shawheen Faghihahmadabadi, Joanna L. Hutchison, Ilana J. Bennett, Michael A. Motes, Robert W. Haley, Bart Rypma
• Format: Article
• Language: English
• Published: Elsevier 2016-01-01
• Series: NeuroImage: Clinical
• Subjects: functional magnetic resonance imaging; dorsolateral prefrontal cortex; Gulf War Illness; processing speed; functional connectivity; cognitive efficiency
• Online Access: http://www.sciencedirect.com/science/article/pii/S2213158216301589

Cognitive slowing is a prevalent symptom observed in Gulf War Illness (GWI). The present study assessed the extent to which functional connectivity between dorsolateral prefrontal cortex (DLPFC) and other task-relevant brain regions was predictive of GWI-related cognitive slowing. GWI patients (n = 54) and healthy veteran controls (n = 29) were assessed on performance of a processing speed task (the Digit Symbol Substitution Task; DSST) while undergoing functional magnetic resonance imaging (fMRI). GWI patients were slower on the DSST relative to controls. Bilateral DLPFC connectivity with task-relevant nodes was altered in GWI patients compared to healthy controls during DSST performance. Moreover, hyperconnectivity in these networks predicted GWI-related increases in reaction time on the DSST, whereas hypoconnectivity did not. These results suggest that GWI-related cognitive slowing reflects reduced efficiency in cortical networks.