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    Tom Brady has never been listed with a concussion. That may be missing the point.

    Concussions among professional athletes make headlines. But that’s only part of the story.

    It’s the hundreds of other little-noticed blows to the head that professional athletes, and especially football players, endure each year that can prove even more problematic, specialists said Wednesday. And the longer an athlete plays, the greater the risk of lasting brain damage.

    That assessment follows a startling announcement from Gisele Bundchen, wife of New England Patriots quarterback Tom Brady, during an interview Wednesday on “CBS This Morning.” Bundchen said her husband “had a concussion last year,” and that “he has concussions pretty much every . . . you know, we don’t talk about it, but he does have concussions.”

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    Brady, at 39, is among the oldest players in the NFL but has apparently never been listed on an injury report with a concussion.

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    Yet with 17 years in the league, preceded by years playing in high school and college, Brady has potentially accumulated thousands of hits. It works in Brady’s favor that he is a quarterback, one of the positions least likely to sustain brain-crunching blows, said Dr. Robert Cantu, a professor of neurology and neurosurgery at Boston University School of Medicine who researches head injuries among athletes.

    Still, the sheer number of years Brady has played may erode any protection conferred by his position on the field, Cantu said.

    “He can’t help his brain by playing football longer,” Cantu said. “Less is better, and some people have genetic and other protective factors at a higher level that seem to get them through no matter what, but most people don’t.”

    In a study published in the Journal of Neurotrauma earlier this year, Cantu and his colleagues found that the total estimated hits absorbed by a player in high school and college was a more accurate predictor of later brain issues than the number of concussions. Among the 93 athletes who were studied, those who played more seasons typically suffered more problems later in life, including depression, apathy, and impaired judgment.

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    Just as headlines tend to focus on athletes’ concussions, similar attention is paid to chronic traumatic encephalopathy, known as CTE, a progressive and degenerative disease found in the brains of many athletes who suffered repetitive head trauma, such as football players.

    But recent studies have found that as many as 16 percent of deceased athletes who played football and other high contact sports, and whose brains showed evidence of CTE, had no reported history of concussions. That has led researchers to conclude the myriad other hits to the head may be a prime culprit in the disease. CTE can cause memory loss, confusion, aggression, depression, and dementia.

    Doctors typically rely on subjective symptoms, such as nausea, dizziness, and confusion, to diagnose a concussion, said Dr. David Brody, a professor of neurology at Washington University School of Medicine in St. Louis. So it is understandable that doctors and patients might disagree on whether a hit to the head caused a concussion, said Brody, who directs a center where retired NFL players receive neurological care. He also treats active athletes in other sports, including boxers and soccer players.

    “It’s perfectly legitimate that [Brady’s wife] might have an opinion about a concussion,” Brody said. “The diagnosis of whether an athlete had a concussion on a particular day really doesn’t matter. We treat the person’s symptoms and try to make an overall decision about whether athletes should return to play.”

    Since 2010, the NFL has adopted substantial changes aimed at curbing head injuries. That means Brady’s career has covered both the more violent time before those rules and the period after, said David Hovda, a professor of neurosurgery and director of the Brain Injury Research Center at the University of California, Los Angeles.

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    “Brady spans a period of time where the rules have changed, the equipment has changed, and the science is more advanced,” Hovda said. “Brady most likely was returned to play [during those earlier years] before he should have.”

    Kay Lazar can be reached at kay.lazar@globe.com.