"Close to 93 per cent were displaying one or more psychiatric symptoms and that at the end of the day doesn't come as a surprise to people in the field," said Dr. Aravind Ganesh, a co-author of the University of Calgary report.
"It goes to show that there is a high risk of mental illness in general that comes with being homeless for a long time."
The study is published in the June edition of The Canadian Journal of Psychiatry.
Calgary is estimated to have the fastest-growing rate of homelessness in Canada. There were 4,060 people without any place at all to live in 2008, the last year for which figures are available.
Researchers used six questionnaires to screen for the most common psychiatric problems in Canada's homeless population. They include substance use issues, anxiety and affective disorders and psychotic illnesses such as schizophrenia.
Interviews were done at the Calgary DI (Drop In) Centre and focused on 166 homeless individuals.
Ganesh said 60 per cent of those surveyed had no recollection of being diagnosed or treated for any form of mental illness. He finds that disturbing.
"This speaks to the need for improved mental-health services for this population at the end of the day."
The report suggests the current way of providing help to a population which is highly transient isn't working.
"Our results ... (argue) against screening as a practical option of selecting particular people for further assessment," it says. "The evident psychological distress ... indicate(s) the immense burden of mental illness in this population."
The report suggests mental-health teams should offer services directly to the homeless rather than screen individuals and then refer them for help.
"One of the things that has been proposed is to have an on-site psychiatrist or an on-site mental-health nurse to help and track these concerns as they come up in the homeless shelters," Ganesh said.
The president of the Calgary Homeless Foundation said the high numbers don't come as a surprise.
John Rook said in Calgary the "Housing First" plan builds in mental health support as the homeless are put into housing.
"I think it's just a problem in the homeless community. When people end up in the homeless system what we try to do is get them housed so we can do assessments that are proper and do the necessary wraparound of support."
Rook said the U of C report is important because it draws attention to the problem.
"You want all the levels of government and agencies working together. It reminds Human Services that there are people with mental illnesses (and) they need to look at health and integrate strategies to make sure people get the support they need."
An official with Alberta Health Services said dealing with problems involving the homeless is part of Alberta's mental health strategy.
"Alberta Health has committed $5 million every year for three years to community based organizations in Edmonton, Calgary and Lethbridge to specifically enhance mental health and addiction services to people who are homeless," said AHS spokesman Howard May.
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