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IF YOU knew you were about to go through a stressful experience, would you pop a pill to protect yourself from its knock-on effects? It’s an idea that has been mooted after a drug seemed to make mice immune to the negative impacts of stressful events. But could we rationalise prescribing such a drug?

We all experience stress during our lives, whether it be a one-off event, such as a loved one dying, or chronic, low-level stress that results from struggling to make ends meet, for example. While most people find ways to cope, for some a particularly stressful event can trigger depression.

What if there was a way to boost our stress resilience and thus shield us from depression? at Columbia University in New York stumbled across the idea while she was giving ketamine to mice with the symptoms of depression.

Even though the ketamine-taking mice had been chronically stressed, when they were dropped in a pool of water – a one-off stressful event – they were unperturbed and kept swimming. Mice not given the drug made no attempt to escape, a classic sign of depression in rodents.

There was also no change in the ketamine-taking animals’ cognitive abilities, which are altered in human depression. “It’s really remarkable,” says Brachman. “They basically look like mice that haven’t been stressed.”

A single dose of ketamine protected mice from developing the symptoms of depression after stressful events for four weeks. But the drug only seemed to stop the symptoms of depression – some of the animals still exhibited anxiety behaviours. “It seems to protect against depression rather than anxiety,” says Brachman, who controversially describes it as a depression “vaccine”. The work will be published in Biological Psychiatry.

If the findings translate to humans, the idea that ketamine could protect us from depression after stressful events is very exciting, says at Yale University.

The drug’s usefulness will depend on how long the effects last, and how well you can predict whether someone’s life is about to get really stressful, says Brachman. “It could be useful for soldiers, or people working in natural disaster environments,” she says. Sanacora adds that it might also be useful for people who have just been diagnosed with a chronic illness.

But not everyone is convinced. Military personnel currently receive psychological training to boost their resilience, but all approaches are experimental, and none has been shown to be particularly effective, says , a trauma psychologist at Tulane University in New Orleans, Louisiana.

And even if we could protect someone from the effects of stress, we might not want to, he says. Stress is a normal part of most people’s lives, and can even be beneficial in some cases. Children who have dealt with stressful experiences tend to be better at dealing with stress later in life, says Figley. “The concern is that we’re medicalising normal behaviour.”

Figley thinks that if a drug were available, it would be almost impossible to know who to give it to. , a psychiatrist at the University of Manchester, UK, agrees. He points out that debates rage over whether to treat teenagers who show the vague behaviour changes that precede the delusions and hallucinations of schizophrenia. Many who have these symptoms don’t develop schizophrenia, so doctors are divided on whether they should be treated with drugs.

“If you knew someone was going into a very stressful situation, if you could find people who were vulnerable and protect them, that would be very useful,” says Anderson. “But you’d have to be selective – you couldn’t just give it to anyone willy-nilly.”

“If you could find people who were vulnerable and protect them, that would be very useful”

Then there’s the use of ketamine – a well-known party drug – itself. Ketamine has been used as an anaesthetic since the 1960s, and has recently been explored as an antidepressant. Most existing drugs take weeks to act, whereas ketamine gives rapid results. It does, however, have downsides: it can bring on hallucinations, and chronic use can and bladder.

Because the idea behind it as a way to build resilience to stress is to only take it in anticipation of stressful events, you would only experience the drug’s negative effects for a few hours, says Brachman.

Ketamine is clinically approved as an anaesthetic so could be used as soon as it is proven to work in people, she says. While Brachman plans to start testing this, she says she will also look for other drugs with similar effects but without the downsides.

This article appeared in print under the headline “A pill to protect against stress?”