Lost productivity caused by workers' depression and anxiety costs the Canadian economy almost $50 billion a year, according to a new report released Thursday.

The Conference Board of Canada said in the report that depression costs the economy at least $32.3 billion annually, while anxiety costs another $17.3 billion a year.

Worker productivity is lost through both absenteeism — when employees are away from their jobs — and presenteeism — when they go to work while sick and perform with reduced productivity, the group says.

Louis Thériault, vice-president of public policy at the Conference Board, said a large proportion of working Canadians have unmet mental health needs that prevent from performing at their peak.

The prevalence of depression varies enormously by industry, with the accommodation, food services and retail trade sectors topping the list, Thériault said.

"[They are] sectors where the labour market is more precarious, job permanency is less [and] there's more turnover," he said.

The report should serve as a wake-up call that employers need to act more strategically about the issue of mental health, he said. While much of the focus on dealing with mental health issues centres on government, attention isn't typically given to the role of employers, he added.

"This highlights the fact that there is a [return on investment]." he said. "There is a gain for the employer in acting … on mental health in the workplace."

The Conference Board's report goes on to say that mental illness can prevent some people from working full-time or part-time, and that almost a quarter of Canadians living with mental health issues are unable to work.

The report adds that if all these Canadians had access to better treatments and supports, the economy could see up to 352,000 Canadians with depression or anxiety enter the workforce as fully functional employees each year until 2035.

In terms of disability benefits, mental illness represents a significant cost to employers, the Conference Board says. It accounts for about 30 per cent of all short- and long-term disability claims, with the value of these claims ranging from $15 billion to $33 billion annually.