In fact, the smokers were almost a decade younger when they were referred to the clinic for treatment — with an average age of 58, compared to an average age of 67 for non-smokers.
The researchers stumbled upon the findings in the midst of another study aimed at finding out whether medication would help people quit smoking.
The study involved 982 people treated at the centre between January 2009 and March 2011. They were at high risk for stroke after having a mini-stroke known as a transient ischemic attack, a suspected TIA or an actual stroke.
Of these, 718 were non-smokers and 264 were smokers.
"We started to look carefully at who these people were that were being referred to us who are at high risk for stroke, how old they were, whether they were men or women, where they came from, and that's what led to this surprise finding," said one of the principal investigators, Dr. Mike Sharma, a stroke neurologist at the Ottawa Hospital.
"We compared the characteristics of the smokers to the non-smokers, and much to our surprise, the smokers were having this disease about a decade younger than the non-smokers."
The findings were unveiled Monday as the Canadian Stroke Congress got underway in Ottawa.
It's an association study that doesn't show cause-and-effect, but Sharma said it is a way of translating the risk associated with smoking into something that people can relate to — time.
Smoking does a few things to blood vessels, he said. There is a hardening and narrowing of the arteries, and blood is stickier.
"When you smoke you have more blood cells and the proteins that clot the blood are increased. So you can imagine if you've got hard narrow blood vessels — thicker blood if you will — that you're much more likely to clog up a blood vessel and cause a stroke," he said in an interview before the conference.
"The other thing that we know about smoking is that even a single puff of smoke makes the arteries stiffer and shoots the blood pressure up."
Risk factors travel together, he noted.
"So that is to say that if you smoke, you may well be likelier to have high cholesterol or high blood pressure or exercise less."
On hearing about the findings, Dr. Felix Veloso, a neurologist in Regina, said he will relay them to his patients in an effort to help persuade them to stop smoking.
"I think what they've been talking about is first-hand smoke, the smoker, but I think that ... second-hand smoke is just as harmful, and spouses exposed to second-hand smoke have about two times the risk of having a stroke," he said.
He said the desire to stop smoking must come from the smoker himself.
"I see this in my practice all the time ... they don't have the will, they don't acknowledge that there's a problem, and that's where we have the difficulty."
"So we have to motivate the patient and I don't know how to do this, except maybe more education."
Among his own patients, Veloso said he sees that smokers suffer from stroke and heart problems and high blood pressure a lot earlier, and a lot worse, than non-smokers.
Sharma said smokers will often suggest quitting will "only make a small difference in my life and what my outcome is."
"In fact, what it looks like here is it can make a big difference. Ten years is a lot of time, when you think about it."
He said information like this might push a person from contemplating quitting to actually doing it.
Co-author Dr. Andrew Pipe of the University of Ottawa Heart Institute said quitting is worthwhile because within 18 months to two years the risk of stroke declines and is similar to that of non-smokers.
According to the Heart and Stroke Foundation, more than 37,000 Canadians die prematurely each year because of tobacco use.
Dr. John Cole, a vascular neurologist at the University of Maryland and Baltimore VA Medical Center, said the Ottawa study provides more evidence that smoking seems to induce stroke at an earlier age.
"I think it calls again for more preventative efforts particularly in a very young population so you can maybe get them to never start smoking in the first place," he said.
Feeling the impact of a major stroke 10 years sooner is significant, he indicated.
"This population's also going to be suffering from those deficits that much longer; it's a major burden obviously on the patient, their family and health-care system in general."