Attention Please! Unravelling the Link Between Brain Network Connectivity and Cognitive Attention Following Acquired Brain Injury: A Systematic Review of Structural and Functional Measures.

Traumatic brain injury (TBI) and stroke are the most common causes of acquired brain injury (ABI), annually affecting 69 million and 15 million people, respectively. Following ABI, the relationship between brain network disruption and common cognitive issues including attention dysfunction is heterogenous. Using PRISMA guidelines, we systematically reviewed 43 studies published by February 2023 that reported correlations between attention and connectivity. Across all ages and stages of recovery, following TBI, greater attention was associated with greater structural efficiency within/between executive control network (ECN), salience network (SN), and default mode network (DMN) and greater functional connectivity (fc) within/between ECN and DMN, indicating DMN interference. Following stroke, greater attention was associated with greater structural connectivity (sc) within ECN; or greater fc within the dorsal attention network (DAN). In childhood ABI populations, decreases in structural network segregation were associated with greater attention. Longitudinal recovery from TBI was associated with normalization of DMN activity, and in stroke, normalization of DMN and DAN activity. Results improve clinical understanding of attention-related connectivity changes after ABI. Recommendations for future research include increased use of electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) to measure connectivity at the point of care, standardized attention and connectivity outcome measures and analysis pipelines, detailed reporting of patient symptomatology, and casual analysis of attention-related connectivity using brain stimulation. Impact statement This systematic review concisely and meaningfully synthesizes a large heterogenous body of research relating to the association between attention and brain connectivity to identify clear trends in traumatic brain injury (TBI) and stroke and recommend a path forward in clinical prognosis in children and adults. We consider a broad range of structural and functional connectivity measures (e.g., diffusion tensor imaging [DTI], functional magnetic resonance imaging [fMRI], electroencephalography [EEG], and functional near-infrared spectroscopy [fNIRS]) and analyses (e.g., voxel- and region of interest [ROI]-based, graph theory, network-based statistics, and others) and examine both cognitive and behavioral measures of attention (e.g., executive, spatial or sustained attention, or inhibition), and conclude with recommendations for further research and clinical practice.