Homelessness is a complex problem with many causes, often including mental illness and alcohol and drug addiction. There may be another component to homelessness shared by many.

Every year, more than half a million teenagers experience a serious concussion. These brain injuries often leave lasting damage, but to what extent?

Brain scans can detect brain disorders. Concussion, a mild brain injury, may be more accurately diagnosed through certain kinds of brain scans than others.

For some injuries, recovery may be a lifelong process that includes risks along the way. Traumatic brain injury may be such a condition.

About 10 million people experience a mild traumatic brain injury across the world each year. Understanding risk factors for these injuries may help with prevention.

Helmets and mouth guards do a lot to protect the head from injury. How well the equipment protects against concussion is another story.

Not so fast. Head injury still bothering you? You might not be allowed to play just yet. "No athlete diagnosed with a concussion should return to play on the same day or while symptomatic," the authors of a recent report said.

Football has always been a dangerous game. Now researchers are learning more about the long-term effects professional players may be experiencing from career-related head injuries.

A bump on the head is sometimes more than just an ouch. Symptoms from a concussion or other mild traumatic brain injury ( TBI ) can last for months or even years.

Hitting the slopes shouldn't involve hitting your head. Though helmets may be bulky and make hearing more difficult, wearing one can protect your noggin and your life.