Former college athletes can show signs of concussion-related brain decline as early as five years after graduation, a new study says.

Athletes who had three or more concussions during college play had worse scores on tests measuring anxiety, depression, distress and sleep quality compared to those without concussions, researchers reported March 11 in the journal Neurology.

These signs of declining brain health were apparent in tests conducted five years after they graduated college, researchers said.

“While the effect sizes of our findings are quite small, the study participants are still young adults in their 20s, so we don’t know if or how these effects might change throughout their lives,” senior researcher Steven Broglio, director of the University of Michigan Concussion Center in Ann Arbor, said in a news release.

For the new study, researchers tracked more than 3,900 former college athletes who participated in 20 different sports, including football, soccer, volleyball, lacrosse, rowing, swimming, tennis and golf.

Of the athletes, 77% had never been diagnosed with a concussion, researchers said. In all, 213 athletes reported three or more concussions; 1,203 reported one or two concussions; and 2,494 reported none.

“Concussions are prevalent among young athletes participating in contact and collision sports,” Broglio said.

“While many studies have examined the effects of concussion immediately after injury or decades later, our study examined the effects in athletes five years after college graduation, a time when early interventions may be more helpful to lessen any long-term effects,” Broglio said.

Researchers performed cognitive and psychological tests on athletes as they started their college sports careers, and again within five years of graduation.

Results showed that those who’d had three or more concussions fared worst on the brain health tests within five years of graduation.

Those with one or two concussions also fared slightly worse than those with no concussions, researchers found.

“It is also important to note that despite the associations, the vast majority of athletes remained within normal clinical levels for brain health,” Broglio said. “Continuing to follow these athletes may help determine if these associations become more or less apparent and meaningful over time.”