Long-term effects of adolescent concussion history on gait, across age

Highlights

• The current study observed individuals with no concussion history after high school.

• Concussion history groups suffered less than 3 (mean) high school concussions.

• No differences in gait variables or fall history between groups, within age.

• Sustaining less than 3 concussions in adolescence has no observable effect on gait.

• Comparing these results to professional athlete concussion history is ill advised.

Abstract

The aim of this study was to examine the possible long-term effects of high school concussion history on gait performance across the lifespan. Individuals with and without a concussion history were grouped into 20-year-old (yo) (n = 40), 40yo (n = 19), and 60yo (n = 18) age groups. Participants completed five trials of four walking conditions: a normal walk, a dual task walk, an obstructed walk, and an obstructed, dual task walk. Spatiotemporal gait parameters for gait analyses during single and dual task conditions. Gait velocity, step width, stride length, percent of time in double support, and obstacle toe clearance were the gait variables assessed along with number correct from dual task. Gait was analyzed via optical motion capture. Data were analyzed by two-factor, multivariate ANOVAs and significant interactions were explored using post hoc contrasts. A significant (F = 2.62, p = 0.03) interaction was observed for the obstructed walk condition. Further analyses yielded no significant concussion history and control group differences, within age. The data indicate that an adolescent concussion history has a non-observable effect on gait across the lifespan.

Introduction

Interest and research in sport concussion has grown dramatically over the previous decade due to the media and political attention to the injury. The findings of these investigations have led to an evolving understanding of injury incidence and the acute and chronic effects of concussion(s). Traditional incidence rates of concussion were thought to approach 250,000 cases annually [1], though advances in understanding the biological underpinnings [2], state legislation [3], and media coverage have resulted in increased injury reporting [4]. The most recent concussion incidence estimates suggest that 1.6-3.8 million concussions sustained during sport and recreation participation annually [5].

A growing body of evidence suggests that concussions can no longer be perceived as a transient injury without long-term consequences [6], [7], [8], [9], [10]. The current literature suggests that in the retired, professional athlete population, with longer lifetime sport exposure and therefore higher lifetime concussion rate have increased rates of depression, dementia, and possibly neurodegeneration [6], [11], [12]. Conversely, the high school athlete, who is unlikely to sustain concussion after adolescence, has been overlooked in this research domain. Indeed, of the 7.7 million high school students participating in athletics each year, only a small percentage progress to the collegiate or professional level. Yet, with incidence rates around 0.25 (per 1000 athletic exposures) for male and female high school athletes and over seven million athletes participating, former high school athletes comprise the largest population of previously concussed athletes [13], [14]. A considerable gap in the literature evaluating persistent cognitive and motor alterations among former high school athletes exists.

In young adults with a concussion history, both cognitive and motor alterations have been observed well beyond clinical recovery from concussion. These altered measures include gait, balance, and neural function [7], [8], [9], [10], [15], [16]. It is widely accepted there is a certain amount of cognitive effort needed for each task and the investment of less than the allotted effort will cause a deterioration of the performance [17]. Increasing balance and gait task difficulty, by including a dual task or obstructed path, elucidates greater alterations in the previously concussed [9], [18], [19], [20]. This could be a function of decreased ability to allocate attentional resources observed in the previously concussed when compared to controls [7], [8]. However, it remains unknown if previously concussed individuals will go on to have divergent gait declines later in life when compared to individuals without a concussion history.

Based on the available data involving individuals with a concussion history, some have proposed an accelerated rate of cognitive and motor decline among the previously concussed when compared to the natural aging process [21]. This idea rises from other accepted behavioral and environmental factors that have a negative influence on neurocognitive or dual task performance [22], as well as natural, negative age-related effects on motor control [23].

The purpose of this investigation was to assess the effect adolescent concussion history on gait, across age. Given the nature of the evidence for long-term effects of concussion, we hypothesize that individuals with an adolescent concussion history will exhibit poorer performance on the dual task component and altered motor performance with age compared to individuals without a concussion history. These decreases will manifest as increased toe clearance, slower gait velocities, a greater percentage of time in double support, and worse recall on cognitive task.