Age of First Exposure to Contact and Collision Sports and Later in Life Brain Health: A Narrative Review

Age of First Exposure to Contact Sports Is Not Associated With Worse Later-In-Life Brain Health in a Cohort of Community-Dwelling Older Men

OBJECTIVE

To evaluate whether early age of first exposure to contact sports (AFE-CS) is associated with worse long-term brain health outcomes.

DESIGN

A cross-sectional, survey study of older men with a history of contact sport participation was completed.

SETTING

Tertiary care facility.

PARTICIPANTS

A cohort of community-dwelling older men dichotomized by using AFE-CS (<12 years vs ≥12 years).

INTERVENTIONS

Independent variables included a dichotomized group of AFE-CS (<12 years vs ≥12 years).

MAIN OUTCOME MEASURES

Brain health outcomes measured by depression, anxiety, cognitive difficulties, and neurobehavioral symptoms. Endorsements of general health problems, motor symptoms, and psychiatric history were also collected. Age of first exposure groups was compared using t tests, χ2 tests, and multivariable linear regressions, which included the following covariates: age, number of prior concussions, and total years of contact sport.

RESULTS

Of 69 men aged 70.5 ± 8.0 years, approximately one-third of the sample (34.8%) reported AFE-CS before age 12 years. That group had more years of contact sports (10.8 ± 9.2 years) compared with those with AFE-CS ≥12 (5.6 ± 4.5 years; P = 0.02). No differences were found after univariate testing between AFE-CS groups on all outcomes (P-values >0.05). Multivariable models suggest that AFE-CS is not a predictor of depression or anxiety. Those in the AFE-CS <12 group had fewer cognitive difficulties (P = 0.03) and fewer neurobehavioral symptoms (P = 0.03).

CONCLUSIONS

Those with AFE-CS <12 to contact sports did not have worse long-term brain health outcomes compared with those with AFE-CS ≥12. Individuals with AFE-CS <12 had significantly lower British Columbia Cognitive Complaints Inventory and Neurobehavioral Symptom Inventory scores compared with those with AFE-CS ≥12.

CLINICAL RELEVANCE

The benefits of earlier AFE-CS may outweigh the risks of head strikes and result in comparable long-term brain health outcomes.

Age of First Exposure Does Not Relate to Post-Career Health in Former Professional American-Style Football Players

OBJECTIVE

Prior studies examining small samples of symptomatic former professional football players suggest that earlier age of first exposure (AFE) to American football is associated with adverse later life health outcomes. This study examined a larger, more representative sample of former professional American football players to assess associations between AFE before age 12 (AFE < 12) and clinical outcomes compared with those who started at age 12 or older (AFE 12 +).

METHODS

Former professional American football players who completed a questionnaire were dichotomized into AFE < 12 and AFE 12 + . AFE groups were compared on outcomes including symptoms of depression and anxiety, perceived cognitive difficulties, neurobehavioral dysregulation, and self-reported health conditions (e.g., headaches, sleep apnea, hypertension, chronic pain, memory loss, dementia/Alzheimer's disease, and others).

RESULTS

Among 4189 former professional football players (aged 52 ± 14 years, 39% self-reported as Black), univariable associations with negligible effect sizes were seen with AFE < 12, depressive symptoms (p = 0.03; η2 = 0.001), and anxiety-related symptoms (p = 0.02; η2 = 0.001) only. Multivariable models adjusting for age, race, body mass index, playing position, number of professional seasons, and past concussion burden revealed no significant relationships between AFE < 12 and any outcome. Linear and non-linear models examining AFE as a continuous variable showed similar null results.

CONCLUSIONS

In a large cohort of former professional American-style football players, AFE was not independently associated with adverse later life outcomes. These findings are inconsistent with smaller studies of former professional football players. Studies examining AFE in professional football players may have limited utility and generalizability regarding policy implications for youth sports.

Contact or Collision Sport History, Repetitive Neurotrauma, and Patient-Reported Outcomes in Early to Midadulthood

CONTEXT

Data on the early to midlife effects of repetitive neurotrauma on patient-reported outcomes have been delimited to homogeneous samples of male athletes without comparison groups or accounting for modifying factors such as physical activity.

OBJECTIVE

To determine the effect of contact or collision sport participation and repetitive neurotrauma on patient-reported outcomes among early to middle-aged adults.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 113 adults (53 [46.9%] men, 60 [53.1%] women; age = 34.88 ± 11.80 years) in 4 groups: (1) physically inactive individuals with no repetitive head impact (RHI) exposure (NON); (2) noncontact sport athletes and nonathletes with no RHI exposure who were currently physically active (NCA); (3) former high-risk sport athletes with an RHI history who were physically active (HRS); and (4) former rugby players with prolonged RHI exposure who remained physically active.

MAIN OUTCOME MEASURE(S)

The 12-Item Short-Form Health Survey (SF-12), Apathy Evaluation Scale-self-rated version (AES-S), Satisfaction With Life Scale (SWLS), and Sport Concussion Assessment Tool-5th Edition (SCAT5) Symptom and Symptom Severity Checklist.

RESULTS

The NON group had worse self-rated physical function than the NCA group as assessed by the SF-12 physical component summary (P = .03) and worse self-rated apathy (AES-S) and satisfaction with life (SWLS) than the NCA (P = .03 for both) and HRS groups (P = .03 and P = .040, respectively). We observed no group differences for self-rated mental health (SF-12 mental component summary; P = .26) or symptoms (SCAT5; P = .42). Career duration was not associated with any patient-reported outcomes.

CONCLUSIONS

A history of contact or collision sport participation and career duration did not negatively affect patient-reported outcomes in physically active, early to middle-aged adults. However, physical inactivity status was negatively associated with patient-reported outcomes in these individuals in the absence of an RHI history.

Efficacy of Guardian Cap Soft-Shell Padding on Head Impact Kinematics in American Football: Pilot Findings

Sport-related concussion prevention strategies in collision sports are a primary interest for sporting organizations and policy makers. After-market soft-shell padding purports to augment the protective capabilities of standard football helmets and to reduce head impact severity. We compared head impact kinematics [peak linear acceleration (PLA) and peak rotational acceleration (PRA)] in athletes wearing Guardian Cap soft-shell padding to teammates without soft-shell padding. Ten Division I college football players were enrolled [soft-shell padding (SHELL) included four defensive linemen and one tight end; non-soft-shell (CONTROL) included two offensive linemen, two defensive linemen, and one tight end]. Participants wore helmets equipped with the Head Impact Telemetry System to quantify PLA (g) and PRA (rad/s2) during 14 practices. Two-way ANOVAs were conducted to compare log-transformed PLA and PRA between groups across helmet location and gameplay characteristics. In total, 968 video-confirmed head impacts between SHELL (n = 421) and CONTROL (n = 547) were analyzed. We observed a Group x Stance interaction for PRA (F1,963 = 7.21; p = 0.007) indicating greater PRA by SHELL during 2-point stance and lower PRA during 3- or 4-point stances compared to CONTROL. There were no between-group main effects. Protective soft-shell padding did not reduce head impact kinematic outcomes among college football athletes.

Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies

OBJECTIVE

Concern exists about possible problems with later-in-life brain health, such as cognitive impairment, mental health problems and neurological diseases, in former athletes. We examined the future risk for adverse health effects associated with sport-related concussion, or exposure to repetitive head impacts, in former athletes.

DESIGN

Systematic review.

DATA SOURCES

Search of MEDLINE, Embase, Cochrane, CINAHL Plus and SPORTDiscus in October 2019 and updated in March 2022.

ELIGIBILITY CRITERIA

Studies measuring future risk (cohort studies) or approximating that risk (case-control studies).

RESULTS

Ten studies of former amateur athletes and 18 studies of former professional athletes were included. No postmortem neuropathology studies or neuroimaging studies met criteria for inclusion. Depression was examined in five studies in former amateur athletes, none identifying an increased risk. Nine studies examined suicidality or suicide as a manner of death, and none found an association with increased risk. Some studies comparing professional athletes with the general population reported associations between sports participation and dementia or amyotrophic lateral sclerosis (ALS) as a cause of death. Most did not control for potential confounding factors (eg, genetic, demographic, health-related or environmental), were ecological in design and had high risk of bias.

CONCLUSION

Evidence does not support an increased risk of mental health or neurological diseases in former amateur athletes with exposure to repetitive head impacts. Some studies in former professional athletes suggest an increased risk of neurological disorders such as ALS and dementia; these findings need to be confirmed in higher quality studies with better control of confounding factors.

PROSPERO REGISTRATION NUMBER

CRD42022159486.

Effects of contact/collision sport history on gait in early- to mid-adulthood

BACKGROUND

To determine the effect of contact/collision sport participation on measures of single-task (ST) and dual-task (DT) gait among early- to middle-aged adults.

METHODS

The study recruited 113 adults (34.88 ± 11.80 years, (mean ± SD); 53.0% female) representing 4 groups. Groups included (a) former non-contact/collision athletes and non-athletes who are not physically active (n = 28); (b) former non-contact/collision athletes who are physically active (n = 29); (c) former contact/collision sport athletes who participated in high-risk sports and are physically active (n = 29); and (d) former rugby players with prolonged repetitive head impact exposure history who are physically active (n = 27). Gait parameters were collected using inertial measurement units during ST and DT gait. DT cost was calculated for all gait parameters (double support, gait speed, and stride length). Groups were compared first using one-way analysis of covariance. Then a multiple regression was performed for participants in the high-risk sport athletes and repetitive head impact exposure athletes groups only to predict gait outcomes from contact/collision sport career duration.

RESULTS

There were no significant differences between groups on any ST, DT, or DT cost outcomes (p > 0.05). Contact/collision sport duration did not predict any ST, DT, or DT cost gait outcomes.

CONCLUSION

Years and history of contact/collision sport participation does not appear to negatively affect or predict neurobehavioral function in early- to mid-adulthood among physically active individuals.

Relating American Football Age of First Exposure to Patient-Reported Outcomes and Medical Diagnoses Among Former National Football League Players: An NFL-LONG study

BACKGROUND

The age of first exposure (AFE) to American football participation is a growing concern for late-life function. Mixed evidence exists surrounding AFE and may be attributed to varied methods employed across studies.

OBJECTIVE

To examine the associations between AFE to American football participation with measures of cognitive, behavioral, and physical function and brain-related medical diagnoses across age categories among former National Football League players.

METHODS

We conducted a cross-sectional survey of 1784 former players (age: 52.3 ± 16.3 years, AFE: 11.3 ± 2.9 years, years of football: 17.5 ± 4.5 years, 86.9% ≥ one lifetime concussion). Players completed a general health questionnaire recording demographics, football playing history (including AFE), and diagnoses (anxiety, depression, any form of dementia, mild cognitive impairment). Players completed Patient-Reported Outcomes Measurement Information System (PROMIS) measures assessing domains of cognitive and physical function, anxiety, depression, sleep disturbance, pain interference, and emotional-behavioral dyscontrol. Multivariable linear and binomial regression models were used to examine the associations of AFE and age with PROMIS outcomes and diagnoses, respectively.

RESULTS

No significant AFE by age interactions were detected for PROMIS outcomes (p ≥ 0.066) or diagnoses (p ≥ 0.147). Younger AFE associated with higher PROMIS scores of anxiety (B = - 0.22, p = 0.016), depression (B = - 0.22, p = 0.010), sleep disturbances (B = - 0.16, p = 0.007), pain interference (B = - 0.19, p = 0.014), and emotional-behavioral dyscontrol (B = - 0.22, p = 0.019). Age was associated with all PROMIS outcomes (p ≤ 0.042). AFE was not associated with the prevalence of anxiety, depression, dementia, or mild cognitive impairment (p ≥ 0.449), while age was (p ≤ 0.013).

CONCLUSIONS

AFE was significantly associated with PROMIS outcomes, albeit low-strength associations (i.e., effect sizes), but not with diagnoses. Our findings indicate AFE is a significant but minor contributing factor for health-related quality of life in this cohort. Future work should incorporate additional characterizations of cumulative head impacts and related factors when examining long-term outcomes associated with football participation.

Examining for Cavum Septum Pellucidum and Ventricular Enlargement in Retired Elite-Level Rugby League Players

Objective

A cavum septum pellucidum (CSP) has been reported as a visible brain anomaly in normal individuals as well in some former combat and collision sport athletes. The appearance of CSP with fenestrations and ventricular enlargement are considered associated features of the neuropathological diagnosis of chronic traumatic encephalopathy. The current study examined CSP anatomic features and lateral ventricle size in retired elite rugby league players and controls.

Methods

Forty-one retired rugby league players and 41 healthy community controls, similar in age and education, underwent structural MRI scans. CSP grade, CSP length, corpus callosum septal length, and Evans' ratio (for lateral ventricle size) were rated by two of the current study authors. All participants also self-reported concussion exposure histories, depressive symptoms, daytime sleepiness, and impulsivity. They completed a neuropsychological test battery assessing premorbid intellectual functioning, attention, processing speed, language, visuospatial skills, memory, and aspects of executive functioning.

Results

The two raters had high agreement for CSP grade (Cohen's κ = 0.80), CSP length [intraclass correlation (ICC) = 0.99], corpus callosum septal length (ICC = 0.73), the CSP/septal ratio (ICC = 0.99), and the Evans' ratio (ICC = 0.75). Twenty-five retired players (61.0%) had an abnormal CSP compared to 17 controls [41.5%; χ(1, 82)2 = 3.12, p = 0.08, odds ratio = 2.21]. The CSP/septal ratio was larger for retired players than for the controls. The Evans' ratio did not differ between the two groups. In the retired rugby league players (n = 41), those with normal (n = 16) and abnormal (n = 25) CSP grades did not differ across age, age of first exposure to collision sport, years of sport exposure, concussion history, or 23 clinical and cognitive variables.

Conclusion

This study revealed a difference in the size of the CSP between retired professional rugby league players and controls. There was no significant difference in the size of the ventricles between the two groups. There were no significant differences between those with vs. without an abnormal CSP on age of first exposure to rugby league, years of exposure to repetitive neurotrauma, number of lifetime concussions, depression, impulsivity, perceived cognitive decline, or on any neuropsychological test.

Football and Dementia: Understanding the Link

Football, also known as soccer or association football, is popular but has a potential link with dementia developing in retired players. The FA and soccer regulators in the USA have imposed guidelines limiting players exposure to heading, despite controversy whether this dementia is caused by heading the ball, a form of mild repetitive head injury (RHI), over many years. Substantial data exist showing that many ex-North American Football players develop a specific neurodegenerative disease: chronic traumatic encephalopathy (CTE), the neuropathological disorder of boxers. In the United Kingdom evidence for the neuropathological basis of footballers' dementia has been slow to emerge. A 2017 study revealed that in six ex-soccer players four had CTE with Alzheimer's disease (AD) and two had AD. A 2019 study showed that ex-footballers were 3.5 times more likely to die from dementia or other neuro-degenerative diseases than matched controls. We argue that in childhood and adolescence the brain is vulnerable to heading, predicated on its disproportionate size and developmental immaturity. RHI in young individuals is associated with early neuroinflammation, a potential trigger for promoting neurodegeneration in later life. Evidence is available to support the guidelines limiting heading for players of all ages, while professional and non-players should be included in prospective studies to investigate the link between soccer and dementia.