An Imperial College of London professor visiting New Zealand says antidepressants are one of the safest medicines in the history of the world.

Claims that antidepressants don't work are dangerous and akin to climate change denial, mental health professionals and experts say.

Stuff reported on a Christchurch conference on Tuesday, in which Cochrane Collaboration co-founder Peter Gotzsche said antidepressants don't work and other speakers questioned the efficacy of the current mental health treatment model.

The Cochrane research organisation has said it did not share the views of Gotzsche on the benefits and harms of psychiatric drugs, according the British Medical Journal.

The Ministry of Health's mental health director says both psychological therapies and medications can be effective for patients.

Views on the issue are dividing the medical community globally.

Imperial College London neuropsychopharmacology professor David Nutt​, who is visiting New Zealand on a William Evans Fellowship with Otago University said views reported from the conference were "inaccurate".

"Antidepressants do work and they're very effective for people who are depressed and anxious. They save lives and reduce suicide risk.

"To say they don't work completely misrepresents the data and denies people access to a potentially life saving treatment."



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Psychiatric drugs had side effects "like any other medication" but modern antidepressants were "one of the safest medicines in the history of the world."

There were long-term trials showing antidepressants were effective, especially to prevent relapse.

There was "overwhelming evidence" supporting the view that mental health problems were caused by chemical imbalances in the brain.

"It's like the climate change debate. Some people do not want it to be true but there is a biological element. It's not a myth. We know the chemistry of depression."

Otago University, Christchurch, head of psychological medicine and Christchurch psychiatrist Professor Richard Porter is one of the author of The Royal Australian and New Zealand College of Psychiatrists (RANZCP) guidelines for mood disorder treatment.

He said the appropriate treatment for mild depression was psychotherapy. For moderate depression, the recommendation was therapy or antidepressants and for severe depression it was both.

"There is no doubt when you look at more severe types of depression that antidepressants are effective," he said.

He was concerned people with severe depression might decide to stop treatment after reading Gotzsche's views, which could put them at greater risk of relapse and suicide.

Psychiatrists were "always questioning what the best treatment is and having robust debates about it" but a "global statement" that drugs don't work was dangerous and unhelpful.

Each patients needed to discuss their needs with their doctors.

"I would caution against discontinuing drugs without having a discussion with your doctor first."

Christchurch mental health nurse Josie Butler said claims antidepressants did not work were "incredibly dangerous" and put lives at risk.

"Speaking both as a mental health nurse and someone who's an anti-depressants, I am very concerned about the impact [these views] will have.

"Antidepressants saved my life and are helpful for countless people."

She agreed that a conversation was needed on the issue of over diagnosis and over prescribing but said it was unwise to say effective drugs did not work.

GP and senior lecturer in general practice at Otago University, Christchurch Ben Hudson said the evidence was clearly showing antidepressants were effective for severe depression.

However, it was "much less clear how effective they are for the moderate to mild depression", which was the majority of cases GPs saw.

"It would be entirely reasonable to say we have been and are overusing antidepressants in the mild to moderate group."

"Because we don't have good access to therapy, and limited access to counselling, it's natural we may feel some pressure and a desire to help and that may lead to a prescription even if the evidence isn't great."

More funding was needed for therapy and counselling, he said.

The Ministry of Health's mental health director Dr John Crawshaw said he had a "robust and respectful exchange of ideas" with a group including Peter Gotzsche.​

Crawshaw said considering a variety of options was important when choosing the best treatment, and clinicians should work with patients and families to balance the benefits and risks of treatments.

International guidelines provided "clear guidance" about using treatments and both psychological therapies and psychiatric drugs, including antidepressants, could be effective in different cases, he said.



RANZCP said it could not comment by deadline. Pharmac declined to comment.