High school athletic associations in the D.C. region are learning to track concussions better, but the sample size may be too small to enact new policy based on the data. (Katherine Frey/The Washington Post)

The safety seminars, tackling clinics, $300 helmets and full-contact practice modifications were just a few of many measures taken by Marshall High’s football staff to reduce head injuries. And they appeared to pay dividends.

The Statesmen’s reported concussions dropped from 33 in 2013 to 31 in 2014. Last fall, the team counted only five, according to Fairfax County Public Schools data. “We’re attacking it from every direction,” Marshall Coach George Masten said. “We did everything humanly possible to try and get our concussions down.”

This is the digestible narrative told by coaches, school administrators and proponents of youth tackle football in Fairfax and around the country — that as a result of hiring athletic trainers, buying state-of-the art equipment and working together with the NFL-backed USA Football to implement safety measures, concussions have fallen dramatically.

But it’s not that simple. Nationally, reported concussions have leveled off after increasing over the past decade; locally, the trends are inconsistent.

A review of data from Fairfax and neighboring D.C.-area school districts reveals a story not necessarily of safer or more perilous playing conditions but of the ever-changing environment in which concussions are being reported. The shifting landscape makes interpreting the data a challenge.

“Whether it’s the awareness or the reporting or the actual techniques that are used, it’s virtually impossible to identify,” said Andrew Lincoln, director of the MedStar Sports Medicine Research Center at MedStar Union Memorial Hospital in Baltimore. “That’s why we’re trying to take this holistic approach in education and training.”

Fairfax has become a poster county for youth concussion safety. In May, FCPS published a news release boasting significant declines in football concussions (43 percent) and injuries (24 percent) since 2013-14.

USA Football, which has championed the popular Heads Up Football safety program, cited those same figures on blog posts, promotional videos and testimonies on Capitol Hill. The organization, however, was widely criticized after the New York Times reported in July that it published questionable data on Heads Up’s effectiveness.

Bill Curran, the FCPS director of student activities and athletics programs, said there were a host of factors contributing to the decline. In 2014, the Virginia High School League instituted a full-contact practice limit of 90 minutes per week. Before the 2013 season, FCPS coaches and assistants completed training in Heads Up, which promotes proper tackling techniques.

“There’s no individual thing,” Curran said. “It’s all part of a full package.”

Fairfax’s report of a dramatic concussion decline since 2013-14, coinciding with a 3 percent participation drop in football, deviates from national trends. Dawn Comstock, the primary researcher into high school injuries and a professor of epidemiology at the Colorado School of Public Health, said concussions increased from 2005-06 through 2012-13, leveled off in 2013-14 and decreased insignificantly in 2014-15.

But FCPS’s recent dip has been significant, even for activities such as cross-country and field hockey. As for why, concussion experts offered several hypotheses: a drop in false positives, a rise in false negatives, reporting error, contact practice limits and culture changes — good and bad — were among the popular ones. Heads Up was not.

FCPS’s concussion database and athletic training program across the county’s 25 high schools make it a popular laboratory for researchers. Lincoln has published multiple academic papers focusing on the wealthy Northern Virginia county, including a 2011 study in the American Journal of Sports Medicine examining head injuries across boys’ and girls’ sports from 1997 to 2008. Concussions quadrupled during that period, but while the data could be indicative of a true increase in brain injuries, it also could suggest greater sensitivity in detection, according to Lincoln. Kids weren’t necessarily getting more concussions; adults were getting better at identifying them.

“That’s the beginning of concussion awareness becoming much more involved in the media and filtering down to parents and players,” Lincoln said.

The lesson in this study — as with another paper linking concussions to protective eyewear in girls’ lacrosse — is that association is not causation.

Counties across the nation are tracking concussion data with varying degrees of accuracy and consistency. For example, in Loudoun County, some schools enter “possible concussions” into the injury management system while others only included confirmed concussions, leading to a wide range in samples, according to Ken Wright, the county’s supervisor of athletics.

In Montgomery County, a reported 35 percent increase in total concussions and an 11 percent increase in football concussions (adjusted for participation) over three years coincides with the expansion of its athletic training program. Twelve high schools had trainers in 2013-14 before the program became county-wide in 2014-15. With more eyes on the sidelines, more concussions were spotted.

“I don’t know what to make of two or three years of data,” said Duke Beattie, Montgomery County director of athletics. “If one school had a significantly large number of concussions a particular year or two years, I don’t know whether that necessarily says something.”

In FCPS, which reported a growth of nearly 22,000 students from 2006 to 2014, concussions rose significantly across all sports after Virginia’s 2010 concussion legislation protecting students with head injuries. Schools and teams reported 1,758 overall concussions in 2013-14 — Heads Up’s first year — a nearly 300 percent increase from 2008-09 (637). West Springfield reported 52 concussions among its 168 varsity, junior varsity and freshmen football players that school year. Other sports’ concussion numbers rose at similar rates; track and field and cross-country combined to increase five-fold from 2008-09 to 2013-14.

Trainers and medical experts speculated a combination of increased awareness and overreporting could have attributed to the steady rise in concussions through 2013-14 and that the subsequent decline could stem from better accuracy in diagnoses.

Symptoms for brain injury and dehydration, for example, can be difficult to differentiate, but trainers are using more quantitative tools to evaluate ocular function, fibular function and balance, leading to fewer false positives.

“ ‘Is he dizzy?’ or ‘Does he have dizziness?’ is now replaced by, ‘What is the sway in center of gravity?’ ” Lincoln said. “We may have been overly cautious [in past years], and this may represent a bit of a swing of a pendulum back to more of a true incidence of concussions.”

Finally, there’s the simple explanation: The true incidence of concussions has decreased, and athletes are experiencing less brain damage. Coaches swear by Heads Up and say that safer tackling techniques, contact practice limits, neck strengthening exercises and better helmets are all contributing to dramatic safety improvements.

Though medical experts have praised proactive approaches such as Fairfax’s, football players remain at higher risk of suffering head injuries than athletes of other sports. In FCPS, football accounts for 11 percent of athletic participants yet is responsible for about a third of reported concussions, a similar rate as 2008-09.

Whether football is getting safer, even the best concussion databases won’t say.

“It’s a wealth of information,” FCPS athletic training program administrator John Reynolds said, “There’s so much there that just, every time we look at it we see something new that’s interesting.”