Chronic traumatic encephalopathy (CTE) was once an obscure entry in medical textbooks. Now, it’s the neurological disease associated with repeated blows to the head, known for afflicting more than 300 former NFL players, and perhaps hundreds more (the condition can only be definitively diagnosed post-mortem).

Many people who had COVID-19 continue to have symptoms well after the initial infection. Here's the latest on possible causes and treatments.

With no consensus on a clinical definition of long COVID, it can be difficult to tell if you have it. Symptoms can include fatigue, shortness of breath, chronic coughing, chest pain, joint pain, and heart palpitations, according to the U.S. Centers for Disease Control and Prevention. Common neurologic signs are cognitive and memory problems known as “brain fog,” headaches, difficulty sleeping, a loss of smell or taste, and depression or anxiety.

COVID-19 pandemic has brought new energy to scientific efforts to restore people’s sense of smell -- Read more on anosmia after brain injury.

Fault Lines investigates how the NFL didn’t compensate players who suffered head trauma playing the most popular US sport.

More and more pro and college athletes are trying on the Q-Collar as they search for something, anything, that might keep their brains safe. But does it work?

ABC News chief medical correspondent Dr. Jennifer Ashton breaks down myths about suicide and how to help someone contemplating self-harm.

Head and neck injuries are rare in track and field, but coaches and professional runners are starting to pay more attention to their effects and how to prevent them.

Traumatic brain injury has largely gone unrecognized, untreated, unnoticed and ignored by the institutions charged with caring for those who bear its weight … as well as those who are left picking up the pieces when that load becomes too great to bear at all.

The Center for Social and Psychological Rehabilitation is trying to help those who have experienced trauma after the Feb. 24 Russian invasion, using dogs like Bice to give comfort. -- Read more on the benefit of dogs for PTSD.