WASHINGTON - Canada and the United States are convening a special forum on mental health after a startling survey found one in six North American adults have been diagnosed with depression.

The effort, announced Thursday by Ambassador Michael Wilson, came with the release of an Ipsos Reid poll on depression in the workplace where 14 per cent of Canadians and 20 per cent of Americans said they'd been diagnosed by a doctor.

Overall, 20 per cent in Canada and 21 per cent in the U.S. said they're either clinically depressed or they think they are but never had it properly diagnosed.

More women than men suffer from it and the illness is more prevalent among those with lower incomes and less education, according to Ipsos Reid.

Eighty-four per cent said companies should make helping employees with depression a key priority.

"It was a bit of a wakeup call," said Ipsos senior vice-president John Wright, noting the survey suggests 23 million people have been diagnosed, including 1.8 million in Canada.

"You're literally looking at a country within a continent."

The bilateral forum will bring scientists and business executives together to devise a "cure and prevention strategy" for major mental illnesses.

"We must be less self-conscious in stating an objective that says we will defeat mental illness," said Wilson, Canada's top diplomat in the U.S.

Wilson has long taken an interest in mental health issues since losing a son to suicide.

The survey reported widespread understanding among people about depression, with 90 per cent believing it's caused by a chemical imbalance in the brain.

Eight in 10 North Americans believe that depression is life-threatening.

Mental illness is rising in the industrialized world, costing some C$300 billion in North America each year.

The forum will consist of a series of conferences starting in Ottawa this fall to establish definite goals to invest more in mental health over 10 years.

Dr. Thomas Insel, director of the National Institute of Mental Health in Bethesda, Maryland, said the forum's "the right idea at the right time for ensuring support for research and the implementation of research findings in both nations."

Bill Wilkerson, who will co-chair the group, said medical advances have ensured that "cure strategies" are no longer an implausible dream.

The telephone survey found evidence of a lot of stigma and fear in workplaces, with 78 per cent of workers saying that people diagnosed with depression should keep it to themselves "for fear of hurting their future opportunities."

Yet many also said company chiefs should help with the issue.

The survey was conducted from Jan. 31 to Feb. 1. among 1,000 Canadians and 1,000 Americans.

The results are considered to be accurate within plus or minus 2.2 percentage points, 19 times out of 20.