I want to make clear that the subject of today’s newsletter is especially difficult.

It involves a Boston University study of athletes who played contact sports — like football — as children and died before turning 30, many by suicide. The Times has just published an interactive article about the study, including childhood videos of the athletes and filmed interviews with their parents.

The article begins with a heartbreaking recording that Wyatt Bramwell, who was 18 at the time, made minutes before shooting himself in 2019. “The voices and demons in my head just started to take over everything I wanted to do,” Bramwell tells the camera as he sits in the driver’s seat of his car. He goes on to ask his father to donate his brain to be studied. Bramwell then tells his family that he loves them and says goodbye.

He was one of the 152 athletes whose brains the Boston University researchers studied. More than 40 percent — 63 of the 152 — had chronic traumatic encephalopathy, or C.T.E., a degenerative brain disease linked to repeated hits to the head. Of the 63, 48 had played football, while others had wrestled or played hockey or soccer. Some had never played beyond high school.

In the interviews with parents, they talk about what they would — or would not — have done differently.

“There is a line between the love of a game and the dangers it presents, and even those who have lost a child cannot agree where it is,” writes the team of Times journalists who produced the article — Kassie Bracken, John Branch, Ben Laffin, Rebecca Lieberman and Joe Ward. “But as we learn more about what contact sports can do to the brain, it may be harder to justify letting children play.”

Although much about C.T.E. remains unclear, the risks clearly seem to rise with time spent playing football or another contact sport. For that reason, many C.T.E. researchers recommend that young children play only touch or flag football. Some experts believe tackle football should not start until high school.