The pharmaceutical industry has largely abandoned drug development for mental illnesses even though depression is a leading cause of disability, experts say.

Authors of papers published in this week's issue of the journal Science Translational Medicine argue that drug discovery for treating psychiatric disorders such as autism, schizophrenia, bipolar disorder and depression are at a near standstill.

"Antipsychotics and antidepressants have been some of the most profitable agents for companies over the last two decades," said Dr. Thomas Insel, director of the U.S. National Institute of Mental Health and one of the authors.

"But that doesn't mean they're effective. What it means is that they sell and they can be marketed."

Sales of antipsychotics and antidepressants reached $25 billion in the U.S. in 2011, Dr. Thomas Insel says. (Dennis Cook/Associated Press)

In the last five decades, more than 20 antipsychotics and 30 antidepressants have been marketed with over $25 billion in sales in the U.S. in 2011 alone, Insel said.

The drugs are descended from serendipitous discoveries such as the mood stabilizing effects of lithium in 1949, said Steven Hyman of Harvard University in Cambridge, Mass., and the author of the second paper.

"The central problem is clear: Neither vast unmet medical need, nor large and growing markets, nor concerted sales campaigns that attempt to recast 'me-too drugs' as innovative can illuminate a path across very difficult scientific terrain," Hyman wrote.

"Advances continue to be made in modes of cognitive psychotherapy and device-based psychiatric treatments; but despite the growing market opportunities, major pharmaceutical companies recently announced substantial cutbacks or complete discontinuation of efforts to discover new drugs for psychiatric disorders."

There are no drugs to target the main symptoms of autism such as social deficits and language disorder, Insel said. Those deficits often respond well to intensive behavioural treatments, which suggests there’s potential for a pharmacological approach.

Antidepressants available today are modestly effective after six weeks of treatment in randomized clinical trials — a long time to wait for a disorder with such a high burden, he added.

Drug needs unmet

"We absolutely need better drugs," agreed Zul Merali, a neuroscientist and head of the University of Ottawa Institute of Mental Health Research. "Unfortunately right now, the first line of treatment when the patients get treated, only about a third of the patients respond really well. The other third show you a mild symptom relief, which really is not much to speak about. And the last third will not respond no matter what you do."

In the cancer field, diagnosis is shifting from being based on clinical symptoms and where it occurs in the body to the DNA signature of the tumour. But the basic biological underpinnings in the brain behind mental illness are poorly understood, Insel said.

Partly that's because the brain isn't as accessible as other organs to study. Other complex diseases such as cancer are often treated with combinations of therapies, but most psychiatric patients receive multiple drugs with little scientific evidence guiding their use, Insel said.

'Unfortunately a lot of these companies are abandoning neuroscience because it's becoming more and more expensive to develop new drugs.'— Dr. Pierre Blier

Rx & D, the group that represents the brand-name pharmaceutical industry in Canada, told CBC News it's not in a position to comment on specific therapeutic areas.

Merali's colleague, Dr. Pierre Blier, a professor in the department of psychiatry at the University of Ottawa and Canada Research Chair in psychopharmacology, is researching the use of new drugs to help people with depression who don't respond to current medications.

"Unfortunately, a lot of the large pharma have dropped out of research, have actually closed down their research centres," said Blier, a psychiatrist at Royal Ottawa Hospital.

"Unfortunately a lot of these companies are abandoning neuroscience because it's becoming more and more expensive to develop new drugs."

Antidepressant medications didn't work for Mandi Luis-Buckner, who says the drugs act like a mask. (CBC)

Blier said mental health has never received the attention or funding as some other medical problems, likely because of the stigma associated with psychiatric illnesses.

Antidepressants made Mandi Luis-Buckner feel like a "walking zombie." After a 27-year career in the financial industry, she was out of work for five years as she began her recovery. Luis-Buckner now works as a return-to-work coach at Sheridan College in Oakville, Ont.

"In my own experience and the experience of people I hear, medication, it's like a mask," she said. "It doesn't really uncover what's really going on inside. There's a lot underneath."

Luis-Buckner said she was sad to hear the pharmaceutical industry is retreating from antidepressants but added that perhaps they've realized the impact of current drugs.

Meanwhile, the public sector is funding research. Merali said the federal government's last budget included a $5-million investment to create a national network for depression research and intervention, which he heads.

With files from CBC's Kelly Crowe and Pauline Dakin