“I was shocked, I’ll be honest with you,” said Jeffrey Bridge, an epidemiologist at the Research Institute at Nationwide Children’s Hospital in Columbus, Ohio. “I looked at it and I thought, ‘Did we do the analysis correctly?’ I thought we had made a mistake.”

The researchers used national data based on death certificates that listed suicide as the underlying cause. In the study, they offered a few possible explanations for the difference, including that black children are more likely to be exposed to violence and traumatic stress, and that black children are more likely to experience an early onset of puberty, which can increase the risk of depression and impulsive aggression. But it was not clear whether those characteristics had changed much over the period of the study and would account for the sharp rise.

Sean Joe, a professor of social work at Washington University in St. Louis, who has studied suicide among black youth and did not take part in the new research, pointed out that suicide had long been one of the few negative health outcomes that have affected blacks less than whites.

A departure from that trend happened from the mid-1980s to the 1990s, when rising suicide rates among black teenagers narrowed the gap with white teenagers. One hypothesis was that the rate was driven up by easier access to guns; another was that there had been a cultural shift, in which young blacks were not as religiously observant as older blacks. In that thinking, religious faith had conferred a protective quality that had made older blacks less vulnerable to suicide.

“What it means to grow up young and black has changed,” Professor Joe said. “Something happened that put black teens at risk.”