Carolyn Dewa remembers a time when her research on mental illness in the workplace often prompted a jarring question.

"Why shouldn't those people just be fired?"

In the not-so-distant past, being diagnosed with a psychiatric disorder could easily spell the end of an otherwise stellar career. Even after successful treatment, stigma and ignorance stood in the way of a professional comeback.

Although change has been slow and the shame persists, Canadian employers are starting to recognize the value of investing in mental health awareness and prevention programs, Dewa, a senior scientist with the Centre for Addiction and Mental Health, told in a telephone interview.

Now, the question is how can companies help employees who are struggling with mental health issues while retaining productivity and a competitive edge.

"What managers really want is guidance," Dewa said. "On one hand, they're beginning to see the scope of the problem...but on the other, they still have to produce."

The impact of mental illness on the economy is undeniable and staggering. The Centre for Addiction and Mental Health estimates that, every week, at least 500,000 Canadians miss work because of a myriad psychiatric issues.

Mental illness is the leading cause of disability in Canada, accounting for about 30 per cent of disability claims. It costs the Canadian economy an estimated $51 billion annually, of which a third is attributed to lost productivity.

And yet, according to a 2010 Institute of Health Economics report, Canada spends less than most developed countries on mental health funding.

There's no doubt that investing in healthy minds is good for business. Dewa's most recent study involving a group of workers in Alberta concluded that those treated for depression were more productive on the job than those who didn't receive any treatment.

But little research has been done so far to calculate the return on investments into workplace mental health programs.

A March 2011 report by the Canadian Population Health Initiative and the Canadian Policy Network at Western University in London, Ont. says there is evidence of payoffs on mental health programs, but not enough quality data on how they manifest in workplaces.

Benefits are hard to measure because they are often indirect and typically seen over a longer period of time, the report notes.

Despite the absence of hard empirical evidence, many experts, business leaders and international organizations argue companies should invest more time and money into mental health strategies.

Among them is Michael Wilson, the former Canadian ambassador to the United States and finance minister who has become a prominent mental health advocate. He and others working with the Mental Health Commission of Canada have made a strong business case for workplace mental health policies.

However, many companies shy away from such programs because they seem "too prescriptive," Claude Di Stasio, a vice-president with the Canadian Life and Health Insurance Association, said in a telephone interview.

"Employers want to do this at their own pace and tailor it to their workplaces. They also don't want to be forced into implementing something that's too costly.

"It's so important...but not everyone is thinking that it should be done," said Di Stasio, who's in charge of CLHIA's mental health portfolio.

That's reflected in a number of surveys suggesting the majority of people feel their workplaces don't do enough to promote mental health.

Di Stasio noted that most Canadian workers covered by some type of health benefits plan already have access to services such as an employee assistance program, which can refer them to a mental health professional.

But those struggling with mental illnesses need more sick leave, and that's where employers are not always accommodating, Di Stasio said.

If you're formally diagnosed with depression, bipolar disorder, or another type of mental illness, your boss and co-workers won't doubt your need to take time off and get help, Di Stasio said.

But a large percentage of people who struggle at work emotionally and psychologically don't necessarily meet diagnostic criteria. They could be reeling from a death in the family, divorce, substance abuse or problems involving their children.

In a "call to action" video posted online, Michael Wilson, who's had vast experience on Bay Street as an executive, says organizations must be "ready, willing and able" to take back employees who've taken sick leave because of a mental illness.

"These people are not damaged goods," Wilson says. "They're an investment to protect and a resource to invest in."

Join the conversation: On Wednesday, Feb. 8 will host a Bell Let's Talk live chat and livestream from 7 a.m. to 5 p.m. ET featuring special guests and experts appearing on CTV News Channel, BNN, and Canada AM.