St. Michael’s Hospital neurologist and researcher Dr. Manav Vyas has always been interested in the mysteries of the brain. ‘It’s almost like a puzzle you’re trying to solve,” Vyas says. “I like the problem solving.”

One of the most confounding mysteries comes in the form of multiple sclerosis, a disease where a person’s immune system attacks the myelin sheath – the protecting covering of nerve cells in the brain, optic nerve and spinal cord – resulting in a range of symptoms that can have massive impact on patients’ lives.

Canada has the largest population of patients with MS in the world, and in a recent study published in Neurology, Vyas examined how the proportion of life spent in Canada correlates to incidence of MS in permanent immigrants to the country.

The results of the study, which followed 1.5 million people who arrived in Canada between 1985 and 2003, suggest immigrants who have spent a greater proportion of their lives in Canada have a greater risk of developing MS than people who have spent a smaller proportion of their lives there.

Throughout the time of the study, 934 people were diagnosed with MS. Study participants who had been in Canada for 70 per cent of their lives were 38 per cent more likely to develop MS than those who had been here for 20 per cent of their lives.

Age may also play a role, with those who arrived before the age of 15 being more at risk.

Vyas says it’s important to look at MS from a global perspective. “We traditionally think of MS as a very Eurocentric disease, but we’re studying people from all over the world,” he says.

While the study does not investigate the causes of MS in immigrants, researchers believe that things like smoking rates, changes in diet and other environmental factors may play a role, as well as social determinants like inadequate access to healthy and affordable foods.

Vyas says studying MS is a long game. It can sometimes feel like every new discovery only creates more questions and mystery. Researchers and clinicians don’t know for sure what triggers MS, and at the moment there isn’t clarity on what can prevent it from happening in the first place.

But it’s also an inspiring journey to be a part of.

“I think the frustration, which becomes hope, is that we’re narrowing down potential factors that might be causative of multiple sclerosis,” says Vyas. “The research is a marathon, and the best discoveries occur when we’re all working together.” n