Mental disorders account for more than half of the hospital stays among the homeless in Canada, says a new report from the Canadian Institute for Health Information (CIHI).

And some emergency room doctors say they lack the resources to properly handle such cases.

"Most of the patients need interventions with social workers, psychologists, psychiatrists," Dr. Ricardo Lobato de Faria, of the Winnipeg Regional Health Authority, told CTV News.

"We really don't that in our ER system at the moment."

In 2005-2006, the study found that mental health disorders accounted for 52 per cent of acute care hospitalizations in Canada (outside Quebec).

Additionally, 35 per cent of homeless people who visited selected emergency departments (EDs), mostly in Ontario, were treated for mental and behavioural related disorders.

That figure is much higher than the 3 per cent of the general population who were treated for similar disorders during the same time period.

The most common problem that EDs dealt with when treating homeless people was substance abuse, accounting for 54 per cent of visits.

Pat Norman said he was driven to the streets of Winnipeg by depression, after the rape of his daughter tore his family apart. And now he tries to treat his sadness with alcohol and cheap drugs.

"It was the pain of what I walked in on. It's a constant flash," he said.

Psychotic disorders, such as schizophrenia, accounted for 20 per cent of visits.

The most common reason for ED visits for the general public is to be treated for injury and poisonings (25 per cent).

Among the general population, the most common reason for hospitalization is for pregnancy and childbirth (13 per cent).

Dr. Jennifer Zelmer, vice president of Research and Analysis at CIHI, said the findings show that the situation with homeless patients is much different than among other Canadians.

"Not everyone with a mental illness is homeless, but it is much more common for people who are homeless," said she said.

The report also notes many factors -- such as housing, income and the ability to cope -- that have been shown to contribute to the onset or duration of homelessness.

"People with severe mental illness may experience limited housing, employment and income options," Dr. Elizabeth Votta, an author of the report, says in the findings.

"On the other hand, people who are homeless tend to report higher stress, lower self-worth, less social support and different coping strategies, factors that are associated with depressive symptoms, substance abuse, suicidal behaviours and poor self-rated health."

With a report by CTV's Jill Macyshon in Winnipeg