"The Brain Behind the Game" : a full reading list for the YouTube episode
- Hope Biosciences
- 3 days ago
- 5 min read
Notes, sources, and more for Stem Cell Revolution's recent deep dive into sports, concussions, and CTE
Hopefully, you've already enjoyed the most recent episode of Stem Cell Revolution (SCR), available on YouTube and Spotify. (If you haven't seen it yet, it's available above. Click here for more episodes on an array of topics, and please check back each month when new conversations drop!). This month, Houston is proud to host the World Cup, which makes it the perfect time to open dialogue about brain health in contact sports.
There's a lot to talk about for both youth and adult athletes, amatuer and professional. We brought lots of numbers to the table - concussion counts, hit counts, the share of donated NFL brains with CTE, our own trial results — and somewhere in the YouTube description, we simply ran out of room! If we met our mission, however, you'll walk away from the episode convinced the issues deserve critical thought, which means you'll want those numbers at your fingertips.
This page constitutes an answer to that anticipated demand, and a tool to continue the conversation. Each and every source cited or referenced on this episode of SCR is found below, in order of mention, with basic context on each information cluster. We hope it's helpful. Want more, or have questions or thoughts to share? Please leave a comment on the YouTube video, and join us in developing solutions.
How big the problem actually is
Americans incur millions of sports- and recreation-related concussions a year. These episode-opening sources examine how injury rates compare across sports, and reveal that in sports where the rules are consistent, girls and women are often concussed at higher rates than boys and men.
References:
CDC / “The Epidemiology of Sport-Related Concussion,” PMC — https://pmc.ncbi.nlm.nih.gov/articles/PMC2987636/
Sports injury statistics, 2025–2026 (AP Sports Editors) — https://apsportseditors.org/sports-injury-statistics/
Sports injury statistics, 2026 (The World Data) — https://theworlddata.com/sports-injury-statistics-in-us/
Football concussion statistics (WifiTalents, 2025) — https://wifitalents.com/football-concussions-statistics/
Sports concussion statistics & public perception (Market.us, 2026) — https://media.market.us/sports-concussion-statistics/
The hits nobody counts
The damage story, however, is not entirely about the concussions we notice. Rather, the most prominent injury story may be about the hundreds of smaller impacts a player absorbs over a season that are moved through or past, and never logged — an estimated 240 a year in youth football, several hundred more by high school, and more than a thousand in college.
References:
Head Injuries & American Football (Ethics Unwrapped, UT Austin) — https://ethicsunwrapped.utexas.edu/case-study/head-injuries-american-football
Reducing Head Impact Exposure in High School Football (ClinicalTrials.gov, NCT04020874) — https://clinicaltrials.gov/study/NCT04020874
CTE risk factors and hits-per-season by level (Headstrong) — https://www.headstrongconcussion.com/cte-risk-factors
What years of play do to the odds
Within the last five-to-ten years, research has convincingly demonstrated that each year of tackle football raises CTE risk by about 30%, and that the cumulative force of total hits — not the number of diagnosed concussions — is what tracks with disease development.
References:
Mez et al., “CTE risk doubles after three years of football,” Annals of Neurology (2019), via BU — https://www.bu.edu/articles/2019/cte-football/
Tripodis et al., “Selection bias may lead to underestimation of CTE risk,” BU School of Public Health (2022) — https://www.bu.edu/sph/news/articles/2022/selection-bias-may-lead-to-underestimation-of-cte-risk-in-former-football-players/
Daneshvar et al., “Number and force of impacts, not concussions, drive CTE risk,” Nature Communications (2023) — https://www.nature.com/articles/s41467-023-39183-0
NIH summary: how football raises the risk for CTE — https://www.nih.gov/news-events/nih-research-matters/how-football-raises-risk-chronic-traumatic-encephalopathy
Why starting young is its own risk
Age-of-first-exposure research reveals youth players, aged 8 to 13, none of whom were diagnosed with a concussion, suffered measurable changes in their brains' white matter by the end of their contact sport season.
References:
BU CTE Center: youth tackle football and earlier symptom onset (2018) — https://www.bumc.bu.edu/camed/2018/04/30/youth-tackle-football-linked-to-earlier-onset-of-cognitive-and-emotional-symptoms-in-athletes-diagnosed-with-cte-after-death/
Washington University Engineering: what a lifetime of football does to the brain — https://engineering.washu.edu/news/2020/What-a-lifetime-of-playing-football-can-do-to-the-human-brain.html
Bahrami / Whitlow et al., subconcussive impacts and white-matter change in youth football, Radiology (2016) — https://pubmed.ncbi.nlm.nih.gov/27775478/
How concussions get measured — and missed
Though there have been laudable strides in concussion treatment as recognition of effects continues to grow, the space between "symptom-free" and "brain-recovered" continues to be overlooked and underreported.
References:
“The NFL Concussion Protocol: A Review,” PMC — https://pmc.ncbi.nlm.nih.gov/articles/PMC10331260/
Baseline concussion testing, explained (HeadCheck Health) — https://www.headcheckhealth.com/blog/baseline-concussion-testing
Concussion underreporting and baseline screening (ChildServe) — https://www.childserve.org/brain-injury-program/concussion-baseline-screening/
Return-to-play testing in asymptomatic athletes, a narrative review, PMC — https://ncbi.nlm.nih.gov/pmc/articles/PMC3838723
CTE and what shows up later
Research into the long-term effects of CTE are sobering. One prominent study finds that of athletes who died before the age of thirty, many already had CTE. Contrary to popular assumption, most of these individuals never played past the amateur level.
References:
BU CTE Center: CTE found in 345 of 376 former NFL players (2023) — https://www.bumc.bu.edu/camed/2023/02/06/researchers-find-cte-in-345-of-376-former-nfl-players-studied/
McKee et al., CTE in young contact-sport athletes under 30, JAMA Neurology (2023) — https://jamanetwork.com/journals/jamaneurology/fullarticle/2808952
NIH: CTE identified in young amateur athletes — https://www.nih.gov/news-events/news-releases/cte-identified-brain-donations-young-amateur-athletes
The soccer data
Though this episode of SCR coincides with the World Cup, the findings transcend a specific season or sport. In one study we referenced, Scottish researchers followed thousands of former professional players for years and found their risk of dying from a neurodegenerative disease was several times higher than the general population; because a later look ruled out obvious lifestyle explanations, the most plausible explanation is sustained and repeated impact to the brain.
References:
University of Glasgow, FIELD study overview — https://www.gla.ac.uk/schools/healthwellbeing/research/shwimpact/headline_1172079_en.html
FIELD (2024): dementia risk not explained by lifestyle — https://www.gla.ac.uk/news/headline_1132176_en.html
Why the damage lingers
As we know from our work in neurodegenerative conditions at Hope Biosciences, inflammation inside the brain that does not simply switch back off after the injury externally heals. One autopsy study found signs of neuroinflammation as late as decades after a single hit. "It was years ago, they're fine now” can be a dangerous assumption when embraced as foundational to research or healthcare.
References:
Ramlackhansingh et al., inflammation and microglial activation after TBI, Annals of Neurology (2011) — https://doi.org/10.1002/ana.22455
Hay et al., blood-brain barrier disruption persisting for years after TBI, J. Neuropathology & Experimental Neurology (2015) — https://doi.org/10.1097/NEN.0000000000000261
Where the science goes next
Hope Biosciences remains committed to developing solutions tor brain injury and degeneration at all levels of severity through FDA-authorized research. Of most recent note, a peer-reviewed piece in Brain presents findings of a 24-patient clinical trial utilizing our proprietary cellular therapeutic, conducted at UTHealth Houston. This is one of two such clinical trials in TBI at UTHealth, backed by the Department of Defense.
Learn more in another SCR episode:
References:
Cox et al., autologous adipose-derived mesenchymal stromal cells for chronic TBI, Brain (Oxford University Press, 2025) — trial NCT04063215 — https://clinicaltrials.gov/study/NCT04063215
MSC secretome in TBI, a review, Surgical Neurology International (2025) — https://surgicalneurologyint.com/surgicalint-articles/the-preclinical-and-clinical-trials-of-mesenchymal-stem-cells-secretome-in-traumatic-brain-injury-review-of-basic-science/
MSCs and extracellular vesicles for neurological disorders, Frontiers in Neurology (2025) — https://pubmed.ncbi.nlm.nih.gov/39974358/
Hope Biosciences opens its first Phase I/II brain-injury trial (BioSpace, 2019) — https://www.biospace.com/hope-biosciences-opens-first-phase-i-ii-stem-cell-trial-for-brain-injury-treatment
DoD-funded Phase II TBI trial expands in Texas (2025) — https://finance.yahoo.com/news/dod-funded-stem-cell-trial-120000195.html
Phase II chronic-TBI trial (ClinicalTrials.gov, NCT05951777) — https://clinicaltrials.gov/study/NCT05951777
Aaaannnddd.....that's a wrap on references and resources from our most recent episode of SCR! Please keep watching, join the conversation, and share widely with your community.
Much, much more hope to come....
