SEATTLE (AP) — A large study is adding to evidence of a link between traumatic brain injuries and dementia later in life.

Repeated injuries and severe ones posed the greatest danger in the study involving 2.8 million people in Denmark. The research was published Tuesday in the journal Lancet Psychiatry.

Overall, the risk was small. About 95 percent of people with a brain injury never developed dementia.

But a single severe brain injury increased the risk of later dementia by 35 percent compared with a person who never had a brain injury. A mild brain injury increased the risk by 17 percent.

Lead researcher Dr. Jesse Fann of University of Washington School of Medicine in Seattle says the findings show that each additional brain injury adds to the danger.