Brain researchers are closing in on a test for chronic traumatic encephalopathy, the degenerative brain disease linked to repeated head hits in NFL players and others that increases the risk for Alzheimer’s disease, depression, suicide, and other mental health problems.

Currently, CTE can be detected only in autopsies, and not in the living. But researchers have made progress in identifying CTE biomarkers that show up on brain imaging tests locating the protein that is the hallmark of the disease in the blood, The New York Times reports.

At a medical conference in Boston this week, Robert Stern, a professor of neurology at Boston University, said technology developed by the company Quanterix had identified higher-than-normal levels of tau proteins in blood samples of 96 former football players.

The results, which are part of a seven-year study funded in part by the NFL, are preliminary because they identify only the total amount of tau in the blood, not the amount linked to CTE. But additional tests are being done to address that issue, Stern said.

He added that the blood samples from the former players suggest that absorbing repeated head hits can lead to higher concentrations of tau in the blood later.

“The more times they hit their head, the higher the tau in their blood,” Stern said. “If you look at the higher levels of plasma tau, you only find them in the N.F.L. players, not the control group.”

In the future, blood tests may be a cost-effective way to diagnose CTE, which could allow patients to know they are at risk and potential take steps to manage, or delay, the onset of dementia, Alzheimer’s, or other issues.

Research projects are also underway to determine if hyperbaric oxygen therapy, or other techniques, can reverse the condition in living patients.

A separate study published in the journal Translational Psychiatry found brain scans performed on a 39-year-old former NFL player who had sustained 22 concussions revealed that the biomarker AV1451 bound to the parts of his brain in the same way as in people diagnosed with CTE posthumously.

The findings, by doctors at the Icahn School of Medicine at Mount Sinai in New York, suggest the biomarker could be used to flag individuals at risk for CTE in the future.