Physical and emotional abuse in childhood may cause changes to DNA that increase the risk of death by suicide, say Canadian researchers, whose findings may one day lead to tests to determine suicide risk, as well as treatments to lower the likelihood of taking one's life.

Every year, one million people end their lives by suicide, leaving friends and family not only mourning the loss of a loved one, but struggling to understand why the tragedy occurred.

A discovery by researchers in Montreal suggests that some suicide victims may have taken their lives because past abuse led to changes in their very DNA.

Researchers at the McGill Group for Suicide Studies have studied the brains of 60 people, many of whom were male suicide victims.

About 40 per cent of them suffered from physical or emotional abuse early in their life. In many of their brains, the researchers found changes to their DNA that impact how their brain cells functioned.

Specifically, changes could be seen in the parts of the brain that manage stress response.

"We believe that experiences early in life, they change certain critical genes and regulation," researcher Dr. Gustavo Turecki, of the Douglas Mental Health Institute at McGill University, told CTV News. "And this leads to development of behaviours, behaviours that increase the risk of suicide."

At first, Turecki and his team identified DNA changes in one gene region in the brain. But that figure has ballooned to 100, making up what is essentially a biological footprint of childhood abuse.

"Early life adversity has an effect not on one gene, but on a lot of genes," researcher Benoit Labonte, of the McGill Group for Suicide Studies, told CTV. "It is a lot more complex than we thought."

The research is part of an emerging field called epigenetics, how environmental factors alter the expression of our genes.

Turecki explains that, while our genetic make-up never changes, our bodies "fine tune" our genetic code as they interact with our environment. The process is known as methylation, and it is what adjusts the expression of our genes.

What is still unclear, according to Turecki, is exactly how these changes alter behaviour, and if that behaviour is what leads to suicide.

Researchers also don't yet know if any changes are permanent.

While both genetic tests to determine suicide risk and potential preventative treatments are a long way off, the research gives scientists a better understanding of a potential cause of suicide.

"We do think these changes are modifiable," Turecki said. "And that there are ways of changing these alterations, leading to the possibility of treating these changes."

With files from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip