TORONTO -- Looking back now, volleyball player Julia Hamer admits she feels like an "idiot" for not recognizing signs of a concussion.
This was back when she was playing for the junior national team at age 19, and was smacked in the head by a volleyball.
It was the second blow in six weeks, the first coming from a dive into the bleachers that put her out of the game for three weeks.
After that first injury -- in which she was diagnosed with a concussion -- she suffered dizziness, confusion, chronic migraines and lost her sense of taste.
The second blow seemed mild by comparison, so she only took a few hours off before returning to the court, despite immediate nausea and dizziness.
"I was a little bit worried but at the same time I thought, 'Oh, I'm probably fine. I couldn't have got a concussion from that, it was just a hit in the head,"' Hamer remembers telling herself.
Five years later, the migraines persist, her sense of smell hasn't fully returned and she's not entirely sure she's regained her full visual acuity.
A new study published Thursday in the Journal of Neurotrauma suggests concussions could be linked to long-term physical changes in the brain.
Researchers from St. Michael's Hospital in Toronto used advanced Magnetic Resonance Imaging (MRI) to examine the brains of 43 male and female university athletes -- 21 with a history of concussion and 22 without.
The study found marked differences in the brains of athletes with prior concussions, including less blood flow to certain areas and smaller frontal lobes -- the part of the brain responsible for decision-making and impulse control.
Athletes with a history of concussions had brain volume that was 10 to 20 per cent less than the athletes who hadn't suffered a concussion. The athletes who had suffered a concussion also had 25 to 35 per cent less blood flow to some areas of the brain, especially the frontal lobes.
"This is the first time to our knowledge that people have looked at changes in brain volume, in blood flow, in white matter all within a single group of athletes," says lead author Nathan Churchill, a post-doctoral fellow in St. Michael's neuroscience research program.
"So we're getting sort of a really comprehensive picture of what's going on after concussion."
The study points to possible long-term health consequences, including the risk of re-injury, depression and cognitive impairments.
And while Churchill says most other studies have focused on a single high-risk sport, this one looked at both contact and non-contact sports including basketball, soccer and volleyball, and found consistent brain differences across the board.
About a year-and-a-half after her second injury, Hamer suffered a mild concussion when she banged her head again -- this time by colliding with her volleyball partner.
She wonders now if she should have taken more time off after that first blow to the head. But she says that's easier said than done when sponsors rely on you and a championship looms.
"You're just so excited to play, you have adrenaline going through, there's pressure from your teammates to go and play," she says, noting she couldn't rely on substitutes because she's in a two-person team.
"There's a different perception of pain and symptoms, I think, when you're a high-performance athlete. It's just a 'get it done' mentality."
Nevertheless, the findings raise questions about how long a suitable recovery period should be.
Churchill says it's clear that concussions are not a short-term injury, even if symptoms like nausea, dizziness, and headaches might only last about a week. He notes that the athletes studied had suffered injuries anywhere from six months to 10 years earlier.
"While I would emphasize this is just a snapshot, this is just a single picture of them in time, it does seem to tell us that whatever's going on, it's long-lasting. It doesn't just vanish after a couple of months."
