Dallas Cowboys player who died by suicide diagnosed with brain disease

In the first stage of the disease, some people also experience short-term memory problems, depression, aggressive tendencies, and executive function issues, according to the CTE Society, a nonprofit group.

In its final stage, a person can experience severe cognition issues and memory loss, as well as dementia, according to the CTE Society.

The disease - which is caused by repeated blows to the head - has been found in the brains of dozens of former National Football League (NFL) players.