Genetic findings in sport-related concussions: potential for individualized medicine?

Assessment of Sports Concussion in Female Athletes: A Role for Neuroinformatics?

Over the past decade, the intricacies of sports-related concussions among female athletes have become readily apparent. Traditional clinical methods for diagnosing concussions suffer limitations when applied to female athletes, often failing to capture subtle changes in brain structure and function. Advanced neuroinformatics techniques and machine learning models have become invaluable assets in this endeavor. While these technologies have been extensively employed in understanding concussion in male athletes, there remains a significant gap in our comprehension of their effectiveness for female athletes. With its remarkable data analysis capacity, machine learning offers a promising avenue to bridge this deficit. By harnessing the power of machine learning, researchers can link observed phenotypic neuroimaging data to sex-specific biological mechanisms, unraveling the mysteries of concussions in female athletes. Furthermore, embedding methods within machine learning enable examining brain architecture and its alterations beyond the conventional anatomical reference frame. In turn, allows researchers to gain deeper insights into the dynamics of concussions, treatment responses, and recovery processes. This paper endeavors to address the crucial issue of sex differences in multimodal neuroimaging experimental design and machine learning approaches within female athlete populations, ultimately ensuring that they receive the tailored care they require when facing the challenges of concussions. Through better data integration, feature identification, knowledge representation, validation, etc., neuroinformaticists, are ideally suited to bring clarity, context, and explainabilty to the study of sports-related head injuries in males and in females, and helping to define recovery.

Genetic Variants and Persistent Impairment Following Mild Traumatic Brain Injury: A Systematic Review

OBJECTIVE

The purpose of this review is to systematically assess primary research publications on known genetic variants, which modify the risk for symptoms or dysfunction persisting 30 days or more following mild traumatic brain injury (mTBI).

SUMMARY OF REVIEW

A search of PubMed and Embase from inception through June 2022 identified 42 studies that associated genetic variants with the presence of symptoms or cognitive dysfunction 30 days or more following mTBI. Risk of bias was assessed for each publication using the Newcastle Ottawa Scale (NOS). Fifteen of the 22 studies evaluating apolipoprotein E ( APOE ) ɛ4 concluded that it was associated with worse outcomes and 4 of the 8 studies investigating the brain-derived neurotrophic factor ( BDNF ) reported the Val66Met allele was associated with poorer outcomes. The review also identified 12 studies associating 28 additional variants with mTBI outcomes. Of these, 8 references associated specific variants with poorer outcomes. Aside from analyses comparing carriers and noncarriers of APOE ɛ4 and BDNF Val66Met, most of the reviewed studies were too dissimilar, particularly in terms of specific outcome measures but also in genes examined, to allow for direct comparisons of their findings. Moreover, these investigations were observational and subject to varying degrees of bias.

CONCLUSIONS

The most consistent finding across articles was that APOE ɛ4 is associated with persistent post-mTBI impairment (symptoms or cognitive dysfunction) more than 30 days after mTBI. The sparsity of other well-established and consistent findings in the mTBI literature should motivate larger, prospective studies, which characterize the risk for persistent impairment with standardized outcomes in mTBI posed by other genetic variants influencing mTBI recovery.

Sport-related concussion research agenda beyond medical science: culture, ethics, science, policy

The Concussion in Sport Group guidelines have successfully brought the attention of brain injuries to the global medical and sport research communities, and has significantly impacted brain injury-related practices and rules of international sport. Despite being the global repository of state-of-the-art science, diagnostic tools and guides to clinical practice, the ensuing consensus statements remain the object of ethical and sociocultural criticism. The purpose of this paper is to bring to bear a broad range of multidisciplinary challenges to the processes and products of sport-related concussion movement. We identify lacunae in scientific research and clinical guidance in relation to age, disability, gender and race. We also identify, through multidisciplinary and interdisciplinary analysis, a range of ethical problems resulting from conflicts of interest, processes of attributing expertise in sport-related concussion, unjustifiably narrow methodological control and insufficient athlete engagement in research and policy development. We argue that the sport and exercise medicine community need to augment the existing research and practice foci to understand these problems more holistically and, in turn, provide guidance and recommendations that help sport clinicians better care for brain-injured athletes.

Systematic Review of Post-Traumatic Parkinsonism, an Emerging Parkinsonian Disorder Among Survivors of Traumatic Brain Injury

This systematic review focuses on an increasing subset of traumatic brain injury (TBI) survivors who develop post-traumatic parkinsonism (PTP), characterized by slowness of movement (bradykinesia), rigidity (stiffness), postural instability, and resting tremors caused by obstruction or damage to deep brain structures of the basal ganglia. PTP is rare, and one hypothesis to explain PTP rarity is that TBIs severe enough to affect deep brain structures are often lethal; however, with increasing survivability of TBIs, these numbers are expected to increase. The goal of this review is to raise awareness of an expected global increase of a subgroup of TBI patients who are treatment responsive and report therapeutic results aiding providers in diagnosing, educating, and treating PTP patients. Literature over the past 100 years was considered, and 44,663 peer-reviewed articles were identified. Inclusion criteria required a clinical indication of parkinsonian signs and TBI. Twenty-six case reports were ultimately included from which 36 individual patient data points were extracted for this review. Between 1980 and 2010, there has been an increase in reporting of PTP decade after decade. Forty-seven percent of PTP cases have 1-6 months of latency to symptom onset, and 83% of cases were male. PTP can occur with or without presence of brain lesions, and the most common type of injuries that cause PTP are motor vehicle accidents followed by falls. PTP patients are responsive to surgery or medication treatments. Further detail on PTP symptomology, treatment responsiveness, and injury types is provided.

Discriminating head trauma outcomes using machine learning and genomics

A percentage of the population suffers prolonged and persistent post-concussion symptoms (PCS) following average head injuries or develops severe neurological dysfunction following minor head trauma. Genetic variants that may contribute to individual response to head trauma have been investigated in some studies, but to date none have explored the use of machine learning (ML) methods with genomic data to specifically explore outcomes of head trauma. Whole exome sequencing (WES) was completed for three groups of individuals (N = 60): (a) 16 individuals with severe neurological responses to minor head trauma, (b) 26 individuals with persistent PCS and (c) 18 individuals with normal recovery from concussion or mTBI. Gradient boosted tree algorithms were applied to the data using XGBoost. By using variants with CADD scores above 15 in the training set (randomly sampled 70%), we identified signatures that accurately distinguish to accurately distinguish the test groups with an average area under the curve (AUC) of 0.8 (SE = 0.019). Metrics including positive and negative prediction values, as well as kappa were all within acceptable range to support the prediction accuracy. This study illustrates how ML methods in combination with WES data have the potential to predict severe or prolonged responses to head trauma from healthy recovery. KEY MESSAGES: Linear association analysis has been inconclusive in concussion genetics. Non-linear methods as boosted trees can offer better insights in small samples. Strong discrimination trends can be achieved from exome data of cases and controls.

Associations between concussion and risk of diagnosis of psychological and neurological disorders: a retrospective population-based cohort study

Objective

To investigate associations between concussion and the risk of follow-up diagnoses of attention-deficit hyperactivity disorder (ADHD), mood and anxiety disorders (MADs), dementia and Parkinson’s disease.

Design

A retrospective population-based cohort study.

Setting

Administrative health data for the Province of Manitoba between 1990–1991 and 2014–2015.

Participants

A total of 47 483 individuals were diagnosed with a concussion using International Classification of Diseases (ICD) codes (ICD-9-CM: 850; ICD-10-CA: S06.0). All concussed subjects were matched with healthy controls at a 3:1 ratio based on age, sex and geographical location. Associations between concussion and conditions of interest diagnosed later in life were assessed using a stratified Cox proportional hazards regression model, with adjustments for socioeconomic status and pre-existing medical conditions.

Results

28 021 men (mean age ±SD, 25±18 years) and 19 462 women (30±21 years) were included in the concussion group, while 81 871 men (25±18 years) and 57 159 women (30±21 years) were included in the matched control group. Concussion was associated with adjusted hazard ratios of 1.39 (95% CI 1.32 to 1.46, p<0.001) for ADHD, 1.72 (95% CI 1.69 to 1.76; p<0.001) for MADs, 1.72 (95% CI 1.61 to 1.84; p<0.001) for dementia and 1.57 (95% CI 1.41 to 1.75; p<0.001) for Parkinson’s disease.

Conclusion

Concussion was associated with an increased risk of diagnosis for all four conditions of interest later in life.

The Retinal Ganglion Cell Response to Blast-Mediated Traumatic Brain Injury Is Genetic Background Dependent

Purpose

The purpose of this study was to examine the influence of genetic background on the retinal ganglion cell (RGC) response to blast-mediated traumatic brain injury (TBI) in Jackson Diversity Outbred (J:DO), C57BL/6J and BALB/cByJ mice.

Methods

Mice were subject to one blast injury of 137 kPa. RGC structure was analyzed by optical coherence tomography (OCT), function by the pattern electroretinogram (PERG), and histologically using BRN3A antibody staining.

Results

Comparison of the change in each group from baseline for OCT and PERG was performed. There was a significant difference in the J:DOΔOCT compared to C57BL/6J mice (P = 0.004), but not compared to BALB/cByJ (P = 0.21). There was a significant difference in the variance of the ΔOCT in J:DO compared to both C57BL/6J and BALB/cByJ mice. The baseline PERG amplitude was 20.33 ± 9.32 µV, which decreased an average of −4.14 ± 12.46 µV following TBI. Baseline RGC complex + RNFL thickness was 70.92 ± 4.52 µm, which decreased an average of −1.43 ± 2.88 µm following blast exposure. There was not a significant difference in the ΔPERG between J:DO and C57BL/6J (P = 0.13), although the variances of the groups were significantly different. Blast exposure in J:DO mice results in a density change of 558.6 ± 440.5 BRN3A-positive RGCs/mm² (mean ± SD).

Conclusions

The changes in retinal outcomes had greater variance in outbred mice than what has been reported, and largely replicated herein, for inbred mice. These results demonstrate that the RGC response to blast injury is highly dependent upon genetic background.

The Future of Concussion

Over the past 2 decades, concussion care is increasingly in demand as research and media attention shed light on the importance of proper diagnosis and medical management to prevent complex, potentially disabling sequelae. The purpose of this review is to discuss the future of clinical concussion care across selected topics under the broad themes of diagnosis/assessment, intervention/treatment, and patient characteristics/presentations with the intent to direct clinicians' attention to important anticipated developments in the field. The current status of biomarkers, clinical settings, models of clinical concussion, return-to-activity, clinical subpopulations, treatment approaches, patient perceptions of injury, and social media are reviewed along with predictions for future developments.

Genetics Influence Neurocognitive Performance at Baseline but Not Concussion History in Collegiate Student-Athletes

OBJECTIVE

This study investigates 4 single-nucleotide polymorphisms [Apolipoprotein E (APOE), APOE promoter, catechol-O-methyl transferase (COMT), and dopamine D2 receptor] that have been implicated in concussion susceptibility and/or cognitive ability in collegiate student-athletes.

DESIGN

Cross-sectional study.

SETTING

Neuroscience laboratory at Elon University.

PARTICIPANTS

Two hundred fifty division I collegiate student-athletes (66 women, 184 men) from various sports.

INTERVENTION

All participants completed Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) testing at baseline concussion testing and had a buccal swab taken for DNA for genotyping.

MAIN OUTCOME MEASURES

Self-reported history of concussions and neurocognitive performance were taken from ImPACT.

RESULTS

Individuals carrying an ε4 allele in their APOE gene had a significantly slower reaction time (P = 0.001). Individuals homozygous for the Val allele of the COMT gene showed significantly worse impulse control scores (P = 0.014). None of the genotypes were able to predict self-reported concussion history in collegiate student-athletes.

CONCLUSIONS

These results indicate that certain genotypes may influence performance on cognitive testing at baseline and that the APOE genotypes may not influence concussion susceptibility as suggested by past studies.

Influence of Concussion History and Genetics on Event-Related Potentials in Athletes: Potential Use in Concussion Management

Sports-related concussions are an increasing public health issue with much concern about the possible long-term decrements in cognitive function and quality of life that may occur in athletes. The measurement of cognitive function is a common component of concussion management protocols due to cognitive impairments that occur after sustaining a concussion; however, the tools that are often used may not be sensitive enough to expose long term problems with cognitive function. The current paper is a brief review, which suggests that measuring cognitive processing through the use of event related potentials (ERPs) may provide a more sensitive assessment of cognitive function, as shown through recent research showing concussion history to influence ERPs components. The potential influence of genetics on cognitive function and ERPs components will also be discussed in relation to future concussion management.