For those who survive, getting back to normal can be very difficult. But a computer first developed to improve memory is now being tested on people recovering from brain injury.
"A 37 foot cabin cruiser came out while I was driving on the water, and I went right into the side of him and I was paralyzed," said 31-year-old Ryan Reitmeyer.
That impact on a Texas lake two years ago crushed Ryan Reitmeyer's skull. His prognosis for survival: grim.
"He was not recognizable; he had taken the full impact of an accident. I looked at the doctor who looked at the cat scan, and I just said, 'Can you save his life?'" said Ryan's father Doug Reitmeyer.
The surgeon told Ryan's father Doug, he thought he could save him, but warned Ryan would likely never speak again, never live independently.
"I said 'You go ahead and save his life and we'll take it from there, because if anybody will prove you wrong, it will be Ryan,'" said Doug Reitmeyer.
Ryan spent two weeks in a coma, more than a month in the intensive care unit. Four months later, through, he was walking again with assistance, and talking -- but he had no memory at all.
Doug recalls leaving a restaurant with his son.
"I was behind him kind of assisting him out, and he looks at me and he says, 'when are we going to eat lunch?' and I said Ryan, 'we just ate lunch.' 'No we didn't, I'm hungry,'" said Doug Reitmeyer.
But Doug didn't give up. He was convinced his son's brain could be rewired with the right tools. His research led him to renowned UCSF neurologist & neuroscience pioneer Michael Merzenich.
"Understand now that the brain is continuously capable of positive change that at any age it can be driven in a corrective direction using the right behavioral approaches," said Dr. Merzenich.
Dr. Merzenich founded Posit Science based on the principal that the brain is a plastic organ and will continue to improve given the right tools.
Posit's Brain Fitness program is one such tool clinical research found the exercises improved memory and processing speed in older adults. Doug Reitmeyer believed the science could help Ryan as well.
"I said 'What if I brought the TBI client to you and you guys can do all the research you want? Just give me access to your tools, research and technology,'" said Doug Reitmeyer.
When Ryan began the exercises, he processed information very slowly.
"He was able to initiate it, but he was pretty primitive and pretty disorganized in his operations and actions. This had a big impact on him, and it really enabled him to respond in a controlled way and it dramatically improved his speech," said Dr. Merzenich.
ABC7's Carolyn Johnson: "So ultimately from baseline to day fifty, what changes did you see?
It was incredible, he went from no memory to having a substantial memory"
"I really love it, it's a great program," said Ryan Reitmeyer.
Ryan's neurophysiologist was guarded about Ryan's potential for progress, given the severity of his injury.
Dr. Jim Misko calls it the most remarkable recovery he's seen in his 20 years of practice. Ryan is now living on his own again, even driving. Dr. Merzenich beleives Ryan will continue to improve, as will the technology posit offers.
"One of the beautiful things about this approach is it's not like a drug where you have a chemical compound which is unchangeable, we can devise a strategy for Ryan and that strategy can be ultimately changed and improved over and over again. Three years from now we will provide much more complete and elaborate training tools for someone like Ryan," said Dr. Merzenich.
More controlled research is needed to prove the program's effectiveness on the brain injured. In the meantime, Posit is partnering with Easter Seals to make its brain fitness program available for free to returning war veterans suffering from brain injury.
"We have a special obligation and duty to these men and women, and we're going to help them," said Dr. Merzenich.
As for Ryan, the love and support of his family, who refused to believe the worst case scenario, no doubt played a major role in his recovery, but his father is convinced Ryan wouldn't be where he is today without Posit science.
"I can't think this company and the people that are in this company enough for all that they've done to help us, and help us believe that all things are possible," said Doug Reitmeyer.
Mike Merzenich, M.D.
225 Bush St, 7th floor
San Francisco, CA 94107