Mapping the Interplay Between Postconcussion Symptoms and Functional Disability After Mild Traumatic Brain Injury: A Network Analysis Across Treatment Care Settings

OBJECTIVE: This study examined the network structure of postconcussion symptoms (PCS) and functional disability in individuals with mild traumatic brain injury (mTBI) managed in primary care versus specialized outpatient mTBI clinics. The study also aimed to identify cross-domain bridging symptoms that may link PCS and functional disability across different care settings. SETTING: Secondary data were drawn from studies conducted in primary care services in Canada and specialized multidisciplinary outpatient mTBI clinics in New Zealand. PARTICIPANTS: A total of 1058 adult participants with a mTBI were included (primary care n = 503; mTBI outpatient clinic n = 555). DESIGN: Cross-sectional networks were estimated separately for each setting using EBICglasso. Strength centrality quantified the interconnectedness of nodes within the PCS and functional disability networks. Combined PCS-disability networks were then estimated, and bridge expected influence calculated cross-domain symptom-function connectivity. Network Comparison Tests evaluated differences in global strength, overall structure, and node-level invariance. Demographic and clinical variables that differed significantly between the primary care and mTBI clinic samples were identified and statistically controlled for in subsequent network analyses. MAIN MEASURES: Postconcussion symptoms were measured using the Rivermead PostConcussion Symptoms Questionnaire and functional disability with the 12-item WHODAS 2.0. RESULTS: Across both settings, frustration and cognitive symptoms (thinking speed and concentration) were the most central PCS nodes, and within the functional disability network, household responsibilities showed the highest centrality. In the combined networks, mood disturbance and slowed thinking speed (PCS) and emotional impact and concentration difficulties (functional disability) were key bridge nodes. Bridge connectivity was higher in the primary care group, with emotional impact and concentration difficulties showing significantly stronger bridging. CONCLUSIONS: Specific cognitive and emotional symptoms appear to play influential roles in connecting PCS and functional disability after mTBI. The strong bridging roles of slowed thinking, mood disturbance, emotional impact, and concentration difficulties suggest potential leverage points for early intervention. These findings generate hypotheses for future longitudinal and experimental research and may support more targeted treatment strategies for individuals with mTBI across different care pathways.