Two studies ask what outside the injury shapes concussion recovery

Concussion return-to-play protocols are written as though recovery is a property of the injury: symptoms resolve, graded exertion is tolerated, the athlete is cleared. Two studies published this month examine factors that have nothing to do with the impact itself — household socioeconomic position in one, childhood adversity in the other — and reach opposite conclusions about whether they matter.

The socioeconomic finding

The first study included high school and middle school athletes from 24 schools in south-east Minnesota who sustained a sport-related concussion between 2020 and 2023 [s1]. For each concussion the researchers recorded date of injury and date of clearance to begin a return-to-play protocol [s1].

Socioeconomic status was measured with HOUSES, a validated index built by matching home addresses to publicly available property data — a method that avoids relying on adolescents or parents to report income [s1]. Scores were divided into regional quartiles, Q1 lowest to Q4 highest [s1].

Among the 132 athletes included (mean age 15.9 ± 1.5 years, 75.0% male), median time to return-to-play clearance was 12.0 days overall [s1]. By quartile it was 16 days in Q1, 12 days in Q2, 13 days in Q3 and 11 days in Q4 [s1].

After adjusting for sex, race, ethnicity, and prior diagnosis of migraine, ADHD, learning disorder and mood disorder, each one-unit increase in HOUSES quartile was associated with an estimated 23.9% fewer recovery days (p < 0.001) [s1].

The gradient is not perfectly monotonic — Q3 sits above Q2 [s1] — which in a sample of 132 across four quartiles is what noise looks like. The regression estimate is the more stable summary, and it is a large effect: roughly five days separate the median in the lowest quartile from the highest [s1].

What the gap probably is not

The obvious interpretation, that lower socioeconomic status produces a biologically worse concussion, is the least likely one. Return-to-play clearance is a clinical decision made by a clinician the athlete has to reach, in a schedule the family has to accommodate. Time to clearance measures access to follow-up as much as it measures healing.

The study does not decompose the gap, and the authors present the association rather than a mechanism. Their conclusion is that return-to-play time may be related to socioeconomic status in young athletes, with higher status associated with shorter timelines [s1].

That framing matters for how the number is read. A shorter clearance time is not automatically a better outcome — clearing an athlete sooner is only good if they are actually ready — but a five-day median gap between the top and bottom quartile in the same 24 schools is more plausibly about the appointment calendar than about the brain.

The null result

The second study looked at a different candidate explanation. Researchers at the Hull-Ellis Concussion and Research Clinic in Toronto enrolled participants referred within one week of injury and followed them for up to 16 weeks [s2]. Recovery was determined by physician assessment of physical, cognitive and sensory functioning; symptoms were quantified with the Sports Concussion Assessment Tool 3, and adverse childhood experiences with the ACE Questionnaire [s2].

Across 256 participants, there was no significant relationship between ACE scores and time to recovery (ρ = 0.18, p = 0.81) [s2].

Secondary analyses did find something, but at a single timepoint. At week 1, ACE scores were associated with SCAT symptom count and symptom severity (ρ = 0.18, p = 0.004 and ρ = 0.19, p = 0.002 respectively) [s2]. Both correlations are weak — a rho near 0.18 describes a faint relationship — and they are secondary analyses, which carries the usual caveat about multiple comparisons.

The authors' interpretation is that exposure to adverse childhood experiences may sensitise individuals to endorsing concussion symptoms in the acute stage without prolonging recovery, and that clinicians should be aware of the impact of childhood trauma when tailoring treatment plans, education and resources after concussion [s2].

Reading the pair

The two studies are not directly comparable. One is a school-sport cohort in Minnesota using an address-derived index of household resources and an administrative outcome — the date of clearance [s1]. The other is a clinic cohort in Toronto using a self-report trauma questionnaire and a physician-determined recovery endpoint [s2]. Sample sizes are 132 and 256 respectively [s1][s2], both modest.

But together they draw a distinction worth holding onto. A social variable that plausibly acts through access to care — socioeconomic position — predicted a large difference in time to clearance [s1]. A social variable that would have to act through symptom perception — childhood adversity — predicted acute symptom reporting and not recovery duration [s2].

Neither result is strong enough on its own to change a protocol, and neither study was designed to test an intervention. What they suggest is that a return-to-play timeline is a composite measurement, and that treating it as a pure index of physiological healing conceals at least one determinant that has nothing to do with the head.

What to watch

The direct test of the Minnesota finding would be a study that separates time-to-first-appointment from time-from-appointment-to-clearance. If the gap sits in the first interval, it is an access problem with an obvious remedy; if it sits in the second, it is a harder question about what differs in recovery itself.

Sources

• Socioeconomic status and concussion recovery in young athletes — The Physician and Sportsmedicine, 2025-11-18
• Impact of adverse childhood experiences on concussion recovery: Findings from the Toronto concussion study — Brain Injury, 2025-11-04