No abstract

The glymphatic system is the macroscopic waste clearance system for the central nervous system. Glymphatic dysfunction has been linked to several neurological conditions, including traumatic brain injury (TBI). Adolescents are at particularly high risk for experiencing a TBI, particularly mild TBI (mTBI) and repetitive mTBI (RmTBI); however, glymphatic clearance, and how it relates to behavioral outcomes, has not been investigated in this context. Therefore, this study examined glymphatic function in the adolescent brain following RmTBI. Female adolescent Sprague Dawley rats were subjected to either three mTBIs or sham injuries spaced three days apart. One-day after their final injury, the animals underwent a beam walking task to assess sensorimotor function, and contrast-enhanced MRI to visualize glymphatic clearance rate. Behavioural measures indicated that the RmTBI group displayed an increase in loss of consciousness as well as motor coordination and balance deficits consistent with our previous studies. The contrast-enhanced MRI results indicated that the female adolescent glymphatic system responds to RmTBI in a region-specific manner, wherein an increased influx but reduced efflux was observed throughout limbic structures (hypothalamus, hippocampus, and amygdala) and the olfactory bulb but neither the influx or efflux were altered in the cortical structures (primary motor cortex, insular cortex, and dorsolateral prefrontal cortex) examined. This may indicate a role for an impaired and/or inefficient glymphatic system in the limbic structures and cortical structures, respectively, in the development of post-concussive symptomology during adolescence.

In terms of cross-sectional correlations, higher levels of baseline pain intensity and interference were associated with higher levels of baseline PTSS (rs = .35 and .36, ps < .001, respectively), more severe insomnia (r = .22, p < .05 and r = .48, p < .001, respectively), and poorer sleep quality (r = -.20, p < .05 and r = -.40, p < .001, respectively), ps < .05. Higher levels of baseline PTSS were associated with poorer sleep quality (r = -.36, p < .001) and more severe insomnia (r = .49, p < .001). Higher pain interference at follow-up was associated with higher levels of follow-up pain intensity (r = .52, p < .001) and 3-month PTSS (r = .25, p < .05). Longer sleep duration was associated with better sleep quality (r = .20, p < .01). Correlations between objectively assessed sleep duration and most of self-report variables were small and nonsignificant (rs ranged from |.02| to |.16|, ps > .05).With regards to longitudinal correlations, higher levels of pain intensity, pain interference, and PTSS at baseline correlated with higher pain intensity, pain interference, and PTSS at follow-up (rs ranged from .24 to .72, ps < .05). Similarly, more severe insomnia and poorer sleep quality at baseline were associated with higher pain intensity, pain interference, and PTSS at follow-up (rs ranged from |.23| to |.43|, ps < .05). Additional Analyses: Child PTSD Symptom scale (CPSS-5) subscales

No abstract