A prominent mental health advocate has demanded national action to protect the public against rogue counsellors and psychotherapists.

Professor Ian Hickie, executive director of the Brain and Mind Research Institute and a key adviser to government on mental health, says Australians are being exposed to damaging treatments because of a lack of national standards and information.

In the absence of regulation, thousands of unregistered counsellors and psychotherapists are free to treat vulnerable clients without proper training or professional supervision.

"We don't allow rogue surgeons to set up in their local garages. We don't allow rogue physicians to just be prescribing medicines anywhere. In the same way, we have to be very clear cut that psychological therapies can do harm," Professor Hickie said.

"Sadly the Australian public is quite vulnerable at the moment because what we have is a really good thing going on, more people seeking help, but on another level, a really bad thing - a real lack of national standards, and a real lack of information about who really has good training, who can be trusted, and those who simply say, 'I'm a counsellor'."

Professor Hickie sounds the alarm in tonight's Four Corners report, which reveals how clients of an unqualified therapist were devastated by false recovered memories of extreme sexual abuse, including rape, incest and paedophilia.

After attending gruelling counselling sessions and retreats with the therapist, a father of two came to believe - and confess - that he had repeatedly raped women, his own children, and friends' children.

Police cleared him when they discovered there were in fact no victims, but not before he had suffered a psychotic breakdown and left his family to protect them from himself.

"I just felt like I was totally worthless and useless and didn't deserve to be alive," the man told Four Corners.

A farmer and his wife were shattered when their three adult children and daughter-in-law levelled a raft of grotesque sexual allegations against them.

The accusers were all clients of the same therapist; all had recovered memories.

The parents endured a 12-month police investigation which found the allegations to be baseless. The family remains split, with two children still in the therapist's thrall.

A young woman undergoing counselling sessions with the therapist was led to believe that she had been raped by her father and her brother, and that she was herself a paedophile.

Another woman describes a plunge into group madness as followers of the therapist began falsely accusing each other of bizarre sexual assaults.

"I could hardly breathe; I was shaking; I was sick; I could hardly speak. I was completely crippled as a person," she said.

Former clients and their families have bravely chosen to speak out on Four Corners to draw attention to the therapist's activities and to the dangers of recovered memories.

Some families have fought for years to get help from government officials but their pleas were ignored.

Tonight's Four Corners exposes the regulatory vacuum that allows untrained operators to flourish.

It also explores the fragility of the human mind. Everyone is suggestible to a degree, according to Professor Hickie.

"When you're distressed, when you're not so well, when you are fragile you are very open to having memories implanted, having the past reconstructed in ways that never occurred," he said.

"People's lives can be put at risk. If you're already vulnerable these treatments make you worse. You can become actively suicidal. You can lose contact with reality."

A forensic psychiatrist has told Four Corners that the therapist's methods amount to guru-like mind control or "primitive brainwashing techniques".

The therapist himself has spoken to Four Corners. In a fiery interview he denies sowing false memories and defends his ideas, his methods and his lack of qualifications.

"I've always had an aversion to qualifications," he said.

"I've learnt through my own experience and through working with thousands of people and getting great success this way. Actually, I don't even want to call myself a therapist, but really just a human being that understands that pain is a natural part of life."