Carotid Arterial Compliance and Aerobic Exercise Training in Chronic Traumatic Brain Injury: A Pilot Study

Abstract

Objective: Decreased carotid arterial compliance (CAC) is associated with cerebral microvascular damage, cerebral blood flow (CBF) dysregulation, and increased risk for stroke and dementia, which are reported to be prevalent after traumatic brain injury (TBI). However, the effect of TBI on CAC has not been reported. The purposes of this pilot study were to (1) compare CAC between participants with chronic traumatic brain injury (cTBI) and age-matched healthy control (HC) subjects and (2) to examine whether CAC changed after 3 months of exercise training in those with cTBI. Setting: Community based. Participants: Nineteen participants with cTBI (6-72 months postinjury) and 19 HC matched for age and sex were tested at baseline. The same cTBI cohort was enrolled in a proof-ofconcept randomized controlled exercise training program to investigate the effects of 3 months of aerobic exercise training (AET) or nonaerobic stretching and toning (SAT) on cerebrovascular parameters. Design: Cross-sectional study and randomized controlled trial. Main Measures: CAC was measured by tonometry and ultrasonography at the common carotid artery; CBF was measured by ultrasonography at the bilateral internal carotid and vertebral arteries, and pulsatile CBF was measured by transcranial Doppler ultrasonography at the middle cerebral arteries. Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by total CBF. Results: Relative to HC, the participants with cTBI had lower CAC (0.10 ± 0.03 vs 0.12 ± 0.03 mm 2 /mm Hg, P = .046) and higher CVR (0.17 ± 0.03 vs 0.15 ± 0.03 mm Hg/mL/min, P = .028). CAC tended to increase after AET compared with SAT (P = .080). Increases in CAC were associated with decreased pulsatile CBF (r = −0.689, P = .003). Conclusion: These findings suggest that the individuals with cTBI have decreased CAC, which may potentially be improved by AET.

Brain changes: aerobic exercise for traumatic brain injury rehabilitation

“…Twelve studies included mixed severities of mild, moderate and/or severe in their aerobic intervention studies ( Bhambhani et al, 2005 ; Brown et al, 2005 ; Schwandt et al, 2012 ; Wise et al, 2012 ; Bellon et al, 2015 ; Chin et al, 2015 , 2019 ; Weinstein et al, 2017 ; Morris et al, 2018 ; Ding et al, 2021 ; Romanov et al, 2021 ; Tomoto et al, 2022 ), all of which reported on adults aged 18–65. Full results can be found in Table 2 .…”

“…Eleven of twelve studies employed aerobic interventions at chronic time points post-injury, ranging from 6 months to 23 years ( Bhambhani et al, 2005 ; Brown et al, 2005 ; Schwandt et al, 2012 ; Wise et al, 2012 ; Bellon et al, 2015 ; Chin et al, 2015 , 2019 ; Weinstein et al, 2017 ; Ding et al, 2021 ; Romanov et al, 2021 ; Tomoto et al, 2022 ), while one study looked at individuals within 3 months of injury ( Morris et al, 2018 ). Intervention timelines ranged between 4 to 14 weeks, with a minimum of two 15-min weekly sessions ( Brown et al, 2005 ), and a maximum of daily activity ( Bellon et al, 2015 ).…”

“…Depending on the study and participant abilities, some interventions offered physical supports (i.e., walking poles, weight assistance). The other half of the studies used multiple types of exercise or allowed participants to choose their aerobic activity based on abilities and preferences ( Bhambhani et al, 2005 ; Schwandt et al, 2012 ; Wise et al, 2012 ; Morris et al, 2018 ; Ding et al, 2021 ; Tomoto et al, 2022 ). Nine of twelve studies tracked participants’ heart rates to ensure aerobic zone adherence, all of which aimed for 60–80% of participants’ maximal heart rates.…”

“…Outcomes of interest varied between studies and included measures of mental health, physical health and abilities, cognition, quality of life, carotid arterial compliance, and feasibility of intervention. Eight studies included at least one measure of physical health or ability, all of which reported improvements across their respective interventions, most commonly improvements in VO2 max and heart rates ( Bhambhani et al, 2005 ; Brown et al, 2005 ; Schwandt et al, 2012 ; Chin et al, 2015 , 2019 ; Romanov et al, 2021 ; Tomoto et al, 2022 ). Six studies included measures related to mental health, with a majority (5/6) reporting improvements in their study-specific measures of stress, depression, quality of life and mood ( Schwandt et al, 2012 ; Wise et al, 2012 ; Bellon et al, 2015 ; Weinstein et al, 2017 ; Chin et al, 2019 ; Ding et al, 2021 ).…”

“…First, it is hard to extrapolate if different effects of intervention would be observed if the studies focused on one severity of brain injury, given the heterogenous needs of adults with mild TBI compared to severe TBI. Many studies in this group were pilot studies, and were likely underpowered ( Bhambhani et al, 2005 ; Brown et al, 2005 ; Schwandt et al, 2012 ; Chin et al, 2015 , 2019 ; Weinstein et al, 2017 ; Morris et al, 2018 ; Ding et al, 2021 ; Tomoto et al, 2022 ), requiring follow-up with full studies. Further, several studies did not include control groups at all timepoints ( Schwandt et al, 2012 ; Wise et al, 2012 ; Bellon et al, 2015 ; Chin et al, 2015 ; 2019 ; Weinstein et al, 2017 ; Morris et al, 2018 ; Ding et al, 2021 ).…”