Mother of 3 woke from a coma thinking she was 15. Years of her life are still out of memory's reach

Seven years ago, Katrina O'Neil was playing baseball when she went into cardiac arrest and was without oxygen for 22 minutes.

Then only 29 years old, she went into a coma for three weeks. When she woke up, she thought she was 15.

"I didn't really recognize the people around me," said O'Neil, who moved to Fredericton four years ago but was living in Cambridge, Ont., at the time of her cardiac arrest. "I reverted back to being a child and just wanted my mom right there. Because that's what my brain was telling me — that I was just a child."

Most of O'Neil's memories of the missing 13 years remain lost.

Her story is now told in a new documentary called Losing Yourself, which is being shown on Accessible Media Inc., by Fredericton filmmaker Robert Gow.

Gow, who runs the production company Vulture's Bluff Productions, played on the same sports team with O'Neil after he moved to Fredericton two years ago. At a bar one night, O'Neil told him her story, and a few months later, he asked her if she would be willing to share it publicly.

"The story came out and I was kind of stunned," Gow said. "And I sat on it for a few months. And then I thought, you know, this would make a really great documentary. And we went from there."

O'Neil said that when Gow asked if she would share her story, her first thought was that nobody would want to hear it. But she was also excited and a little scared to show people what she had been through.

When she woke up from her coma, O'Neil said, she felt confused because she had lost 13 years of memory. She also had trouble retaining information at first.

Reverting back to when she was 15 years old meant O'Neil didn't remember her three children or their births.

They were one, seven and 10 years old when the coma happened.

Condition rare but not unheard of

Dr. Howard Chertkow, a cognitive neurologist and the senior scientist at Rotman Research Institute at Baycrest Centre in Toronto, said a situation like O'Neil's is rare, but it isn't unheard of.

He said he once had a patient with an almost identical story.

Chertkow said the hippocampus, a complex brain structure in the temporal lobe that plays a big role in memory, was likely affected by the lack of oxygen.

"Something special about the hippocampus is that it's very sensitive to lack of oxygen," Chertkow said in an interview. "Because when the brain stops getting oxygen, it becomes acidotic. That means that the pH level of the brain goes down."

He said the hippocampus is very sensitive to acidosis, so the cells break down, stop functioning and die within only a few minutes.

Even when the hippocampus is damaged, the rest of the brain is still viable, he said, which is why certain things like O'Neil's movement, sensation or procedural memory wouldn't have been affected.

Motor memory remains intact

Procedural memory, sometimes called motor memory, has to do with learning how to do things. Chertkow said this type of memory doesn't need the hippocampus in the same way and relies more on the part of the brain called the cerebellum.

O'Neil was a bus driver before the injury and while she doesn't remember her training, she said, she has sat in a bus since losing her memory and has known where the air brakes were and many of the operational parts.

Chertkow said long-term memories aren't stored in the hippocampus, but the hippocampus acts as a gateway and the memories are in a network in the cortex and the surface of the brain.

"The long-term memories from before the accident are still there in her brain," he said. "She just can't bring them to consciousness."

O'Neil said small bits of her memories have come back, but much of what she knows now she's learned from other people since her coma.

"I'm told all these stories of who I am, but I don't remember any of it," she said.

During recovery, O'Neil's mom and aunt took care of the kids. But when she was ready to care for them again, she said, it was overwhelming and frustrating at times.

"Everybody threw all this responsibility at me that I didn't even know how to deal with yet," she said. "I'm very lucky that my kids, they were patient with me, they worked with me, they understood that things just weren't the same anymore. But the biggest thing for them is that they just wanted to be with their mom."

O'Neil said one of the more difficult parts of filming the documentary was sitting down and looking at pictures from the past.

"I just wanted to remember so bad why my kids were so happy in this picture," she said.

And now, even seven years later, O'Neil said, it still hasn't become easier to talk about. When it comes to strangers, she has her story down to a "Reader's Digest version," but she still finds it hard to speak in depth with people who care about her.

"I don't know really what to always say," she said. "And I just, I feel lost with it. Sometimes it's like people want answers, and I just don't know how to answer them, because I just don't know."