Resting-state functional connectivity after concussion is associated with clinical recovery

Abstract

There has been a recent call for longitudinal imaging studies to better characterize the time course of physiological recovery following sport-related concussion (SRC) and its relationship with clinical recovery. To address this, we evaluated changes to resting-state functional connectivity (rs-FC) of the whole-brain network following SRC and explored associations between rs-FC and measures of clinical outcome. High school and collegiate football athletes were enrolled during preseason. Athletes that suffered SRC (N = 62) were assessed across the acute (within 48 hr) and sub-acute (days 8, 15, and 45) phases. Matched football athletes without concussion served as controls (N = 60) and participated in similar visits. Multi-band resting-state fMRI was used to assess whole-brain rs-FC at each visit using network-based statistic and average nodal strength from regions of interest defined using a common whole-brain parcellation. Concussed athletes had elevated symptoms, psychological distress, and oculomotor, balance, and memory deficits at 48 hr postconcussion relative to controls, with diminished yet significant elevations in symptoms and psychological distress at 8 days. Both rs-FC analyses showed that concussed athletes had a global increase in connectivity at 8 days postconcussion relative to controls, with no differences at the 48-hr, 15-day, or 45-day visits. Further analysis revealed the group effect at the 8-day visit was driven by the large minority of concussed athletes still symptomatic at their visit; asymptomatic concussed athletes did not differ from controls. Findings from this large-scale, prospective study suggest whole-brain rs-FC alterations following SRC are delayed in onset but associated with the presence of self-reported symptoms.

Keywords: athletes; functional MRI; mild traumatic brain injury; postconcussion symptoms.

© 2018 Wiley Periodicals, Inc.

Figures

Figure 1

Clinical measures and average nodal strength. Shown are mean scores for core clinical measures (a) and average nodal strength (b) for concussed athletes as well as contact control athletes at baseline, 48 hr (48H), 8 days (8D), 15 days (15D), and 45 days (45D). Error bars represent standard error of the mean. SCAT3 = Sport Concussion Assessment Tool‐3; BESS = Balance Error Scoring System; BSI‐18 = Brief Symptom Inventory‐18 Global Severity Index; ImPACT = Immediate Postconcussion Assessment and Cognitive Testing

Figure 2

Network‐based statistic results: whole group analysis. Shown are the nodes (i.e., regions of interest) and edges (connections) of networks in which concussed athletes had significantly greater connectivity than controls at the 8‐day visit. Edges are colored based on t‐stat values. Nodes and edges are projected onto the MNI standard template brain using BrainNet Viewer. Nodes are displayed via a sphere at the center of mass for each ROI. L = left; R = right [Color figure can be viewed at http://wileyonlinelibrary.com]

Figure 3

Network‐based statistic results: sub‐group analysis. Shown are the nodes (i.e., regions of interest) and edges (connections) of networks in which symptomatic concussed athletes had significantly greater connectivity than controls at the 8‐day visit. Edges are colored based on t‐stat values. Nodes and edges are projected onto the MNI standard template brain using BrainNet Viewer. Nodes are displayed via a sphere at the center of mass for each ROI. L = left; R = right [Color figure can be viewed at http://wileyonlinelibrary.com]