In 2012, former super heavyweight kickboxer and heavyweight mixed martial artist Gary Goodridge was diagnosed with degenerative dementia – a type of Chronic Traumatic Encephalopathy, or CTE. “It sneaks up on you,” he told Inside MMA. “It’s like a shark in the water that you can’t see.”

Goodridge, who has a penchant for flashlights because he “loves the light,” lives in a very dark place mentally. He said if it were not for his meds, he would have committed suicide. “It’s got me crippled,” he explains as he bouts with a disease that strangles his brain cells, causing memory loss, speech problems and explosive behavior.

Former college football player Michael Keck probably could have related to Goodridge before his life was cut short at 25. He was diagnosed with CTE – the Alzheimer’s-like disease that former San Diego Charger linebacker Junior Seau suffered from. Seau ended his own life with a bullet through the chest.

Boston University describes CTE as a progressive degenerative disease of the brain found in athletes and others with a history of repetitive brain trauma. CTE has been known to affect boxers since the 1920s – some referred to back in the day as “punch drunk.”

Recent reports have confirmed CTE in many retired professional football players and high-impact athletes. According to Boston University, trauma triggers progressive degeneration of the brain tissue, including the build-up of an abnormal protein called tau. Tau is characterized by brown spots that form around the brain’s blood vessels, interrupting normal functioning and eventually killing nerve cells. These changes in the brain can begin months, years, or even decades after the last brain trauma or end of athletic involvement. The brain degeneration is associated with memory loss, confusion, impaired judgment, impulse control problems, aggression, depression, and eventually, progressive dementia.

Dr. Ann McKee, chief of neuropathology at the VA Boston Healthcare System, has worked with a team to evaluate 170 brains to understand the pathology of CTE. She also evaluated Keck’s brain. She never saw that kind of brain pathology in someone under 30. Keck played football for 16 years, starting at the tender age of six. Reportedly, he had more than 10 concussions – with the very first one at eight – and never received treatment. (Source: CNN)

A star athlete and stellar student, he received several offers to play college football, but opted for the University of Missouri in Columbia. During his freshman year, he suffered a concussion on the field as a result of head trauma, where he lost consciousness. Headaches, neck pain, insomnia, and anxiety persisted. He couldn’t remember things or concentrate. Keck returned to the field a few days afterward — with symptoms intact. By the beginning of his junior year, now at Missouri State, he hung up his cleats. His G.P.A. plummeted to 1.9 and he eventually dropped out of school with just 12 credits left to earn a bachelor’s degree.

Life and daily living took a turn as well. Keck became increasingly depressed, suicidal, and abusive to his wife, Cassandra. The marijuana he used did little to dilute the anxiety and headaches. Keck knew something was wrong. He studied the similarities he shared with Seau. He also heavily researched CTE. Keck believed he had it.

Dr. Greg Canty, a sports medicine physician at Children’s Mercy Hospital, told accessHealth, “The challenging part about CTE is that it can’t be diagnosed in anyone who is living. There’s a lot of debate in the medical community, like sports medicine, neurology and neurosurgery. Is this a new disease process, or is this re-describing something old? It appears to be something that we’ve known about for years because of some chronic changes in the brain. What we don’t know is exactly what leads to CTE. There is no direct evidence that having a concussion leads to CTE.”

Canty stresses that there is a lot of gray area when it comes to CTE. He said that although concussions are a problem and that the medical community worries they may be related to CTE, they don’t know that definitively. “Most people don’t understand there is not a direct correlation that has been proven yet.”

The other potential unknown is whether CTE is related to small, repetitive hits to the head or a big hit that leads to a concussion. Canty underscores one major fact: there are more questions about CTE than answers. As for Keck, he was so convinced that he had the disease, he told his wife that if he died to donate his brain to Boston University. Keck died from cardiac arrest in 2013.

He was diagnosed postmortem with CTE.

Canty said that improving athletic safety is number one. But what worries him are the people who automatically assume because they’ve had a concussion and maybe had a few neurological symptoms that they are definitely on the pathway to having CTE. This includes those 22-year-old athletes who may have had a few concussions, and begin having headaches, and forget where they placed their keys. Many of them start to wonder.

“In some situations, people have committed suicide because they were convinced that all of their problems were a result of CTE,” he said. “We just don’t know that yet. What we do know is that most concussions recover without incident.”

Canty also said there is a large population of people with mental illness and depression who can be treated. People could forget things and have a completely normal memory. Unfortunately, he says, the CTE fear can sometimes become a “self-fulfilling prophecy. “They see themselves on a slow, gradual decline and they do things not understanding the real lack of medical knowledge about the disease.”

There may be some mitigating factors for depressed athletes besides CTE, especially after they retire. “For some, it is because of random steroid use; for others, it may be the fact that they used to be a superstar, but they are not any longer. And for others, divorce and bankruptcy may play a role in depression.” Canty said these stressors and life changes are not necessarily a result of head trauma. “There are other forms of dementia, other forms of depression, and other types of illnesses that can present with very similar symptoms as to what people suspect they are having when they have a post-concussion or chronic head injury.”

However, a recent study published by Frontline concluded that 95.6 percent of deceased NFL players tested positive for CTE. Specifically, the research concluded that in a pool of almost 100 deceased NFL players, over 95 percent tested positive for CTE. The research was carried out by the Department of Veterans Affairs and Boston University.

“People think that we are blowing this out of proportion, that this is a very rare disease and that we are sensationalizing it,” McKee told CBS Sports. “My response is that where I sit, this is a very real disease. We have had no problems identifying it in hundreds of players.”

To add insult to injury, the study noted new evidence that suggests the minor head trauma that occurs regularly in football may pose a greater risk than the more pronounced concussion that comes with high impact.

Canty said concern is necessary, but it is important for the medical community to look for more answers. “I do have concern for kids who hit their head too much or have a concussion and go back and play prematurely,” he said. “I worry about those things. I also worry about my kids driving a car, texting on their phone – you worry about a lot of things. So, when you look at the relative risks in life, sports are still safe.”

Quality of life among athletes is something that Canty said shouldn’t be overlooked. He said there are many positive lifestyle characteristics that have a direct correlation with sports involvement, but agrees it is also imperative to find ways to make all sports safer. Some precautions have already taken shape. Canty notes moves to eliminate unnecessary contact to the head and limiting the number of contact practices for starters. He also urges athletes never to return to play after a concussion until they have been fully cleared by a medical professional who has experience with the condition.

When asked if he has seen more concussions over the past decade, Canty said yes. However, he said it’s not necessarily because more athletes are having more concussions. Instead, he says there is more awareness and recognition of how a concussion presents. Canty believes even with the concern and fear about the condition, medicine has to push for better ways to diagnose concussions and find out if concussions are related to CTE, or if it is just the opinion of a couple of people with really big microphones.

“I worry that there is some risk to these athletes who have hit their heads over and over and over again – but we don’t know yet,” he said. “On the other hand, there’s a lot of benefit to sports and games that these kids play and there are a lot of life lessons. Kids rank their quality of life better if they are involved in these sports, so we want to keep them active and playing. We just want to find the safest way to do that.”

As for CTE, Canty said that for the most part, people with the condition have been mostly older-aged athletes. There are still questions as to how that applies to the 16-or 17-year-old athlete.

“There have been some descriptions of young athletes who passed away and had their brain examined and demonstrated signs of having CTE,” he acknowledges. “But again, CTE remains a bit controversial and highly debated.”