Neurovascular coupling response is maintained despite exposure to repetitive sub-concussive head trauma over the course of one contact-sport season

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Abstract

Objective

To examine how head-impact exposures affect the elevation in cerebral blood velocity (CBV) in the posterior cerebral artery (PCA) during visual tasks.

Design

Prospective Cohort.

Setting

Laboratory.

Participants

To date: 40 male contact-sport athletes (19.4±1.2 years) and 3 cross-country athletes (20.0±1.0 years) have completed testing (non-contact controls).

Intervention

Transcranial Doppler ultrasound indexed PCA CBV during visual tasks. Participants closed their eyes (20-seconds), and when prompted, opened them and completed a visual task (40-seconds). Testing occurred prior-to and upon-completion-of the competitive athletic season. Raw traces from each trial were averaged to enhance the signal-to-noise ratio of outcome measurements. Independent variable tested was time (2).

Outcome

Eyes-closed CBV (cm/s), peak elevation in CBV (cm/s), relative change in CBV (%) and total activation during the first 30 seconds of the task (indexed via area under the curve-AUC). Head-impact exposure was characterised in a subset of contact-sport athletes (n=29) using the xPatch (X2 Biosystems).

Main results

RM-ANOVA indicated the contact-sport season had no effects on any outcome metrics: Eyes-closed CBV (p=0.181), peak CBV (p=0.117),% CBV elevation (p=0.252) and AUC (p=0.366), despite experiencing cumulative peak linear accelerations of 8147.2±6215.5 g, and cumulative peak rotational accelerations of 34.5×106 ± 59.0×106 rad/?s2.

Conclusions

The results from this study suggest neurovascular coupling metrics are maintained throughout a contact-sport season. This indicates nutrient delivery is maintained for neurocognitive challenges despite possible impairments in cerebrovasculature’s ability to buffer blood pressure challenges associated elevations in rotational accelerations experienced during a contact-sport season.

Competing interests

None.

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