Boarding an airplane within 72 hours of a concussion may not influence the severity of symptoms or the recovery process, according to a new report.

College athletes and military cadets, in particular, could benefit from additional guidelines about when to fly after they’ve experienced a concussion, the authors write in JAMA Network Open.

“Athletes fly to and from games several times during a season. It is important to know if flying shortly after sustaining a concussion may affect their recovery and prevent them from completing their season,” lead author Dr. Tara Sharma of the University of Washington Medical Center, in Seattle, told Reuters Health by email.

Concussions, which are a form of mild traumatic brain injury, often lead to symptoms such as headaches, dizziness, fatigue, irritability, insomnia and difficulty with concentration and memory. Studies have shown that symptoms can deepen due to sleep deprivation, certain drugs, dehydration and psychiatric disorders such as anxiety and depression.

Airline passengers are exposed to decreased oxygen pressures during flights, Dr. Sharma explained, which can reduce oxygen-saturation levels and could potentially influence neuroinflammatory responses in people who have recently had a concussion.

She and her colleagues analyzed data from the National Collegiate Athletic Association and the U.S. Department of Defense concussion database, which included nearly 3,500 varsity athletes and military service academy cadets who experienced a concussion between 2014 and 2018.

They looked at symptom severity and symptom recovery among 165 people who flew and 2,235 who didn’t fly within 72 hours of injury and paid additional attention to those who flew across multiple time zones. The median flight time was two hours, and the median time between concussion and flying was 12 hours.

Overall, flying soon after a concussion wasn’t associated with headache severity, symptom severity or recovery, including the number of days until a return to play or a return to school.

Nor was there an association between flight time or the number of time zones crossed and symptom recovery or symptom severity.

When looking at football players only, the researchers found that those who flew didn’t have significant differences from those who didn’t fly in terms of their return to play, return to school, symptom severity or symptom recovery.

“We were surprised since many of the animal studies done on this topic have shown that hypobaric pressure could worsen clinical outcomes,” Dr. Sharma said. “It is still possible that flying may temporarily exacerbate symptoms . . . but we can say that flying may not prolong overall recovery from concussion.”

A potential explanation is that pressurized cabins may reduce the physiological problems that stem from low pressure and high altitude, the authors write. Even if oxygen saturation dips slightly, it may not be enough to lead to worse health outcomes.

In addition, healthy, fit people such as trained athletes and military cadets may be more likely to acclimate to the physiological changes that occur during flight.

A limitation of the study is that the symptom evaluations didn’t occur immediately after flights, so the research team can’t say whether flying affects short-term concussion symptoms. In addition, only a small number of athletes flew within six hours of injury, took long flights or crossed multiple time zones.

Future research could indicate whether flying immediately after a concussion, cross-country flights or international flights are more likely to affect concussion recovery.

“Oxygen saturation declines significantly in athletes during long-haul commercial flights, in response to reduced cabin pressure,” said Dr. Celeste Geertsema, a sports medicine specialist who has worked with numerous national and international teams in New Zealand. Dr. Geertsema, who wasn’t involved with this study, has previously researched the effect of commercial airline travel on oxygen saturation in athletes.

“The concern is that altitude exposure may exacerbate hypoxemia,” which can affect blood flow in the brain, said Dr. Geertsema, who is now with Aspetar Qatar Sports and Orthopaedic Hospital in Doha. “Several studies have documented the immediate and delayed physiological effects of altitude exposure, but longer-term changes still remain unclear.”