Long-term use of antidepressants helps to reduce risk of relapse, study finds

More than 1.5 million individuals in England have been on antidepressants for two years or more

More than 70 million antidepressants were dispensed in England in 2020 (Getty)

The long-term use of antidepressant drugs helps to reduce the risk of relapse for people who have suffered from recurrent depression, according to new research.

In what is the first study of its kind, scientists at University College London showed that 56 per cent of people became depressed again within 12 months after they stopped taking antidepressants, following years of use.

By comparison, only 39 per cent of people who continued to take their medication during the same one-year period experienced a depressive relapse, the research found.

The number of antidepressants dispensed by GPs in England has increased in recent years, rising from 30 million in 2005, to 61 million in 2015, to 76 million in 2020.

This has been fuelled by an increase in the length of time that people are taking their medication for. More than 1.5 million individuals in England have been on antidepressants for two years or more.

Evidence on the long-term benefits of antidepressants has been limited in recent years. “Until now we didn’t know whether antidepressant treatment was still effective when someone has been taking them for many years,” said Dr Gemma Lewis, a lecturer in mental health studies at UCL and lead author of the study.

“We have found that remaining on antidepressants long-term does effectively reduce the risk of relapse.”

The research, published in the New England Journal of Medicine, involved 478 patients who had been taking long-term antidepressants and suffered at least two or more episodes of depression. Some 70 per cent had been taking the medication for more than three years.

In a randomised, double-blind controlled trial, half of the study participants stopped taking their medication and half continued. Those who discontinued their antidepressants were given reduced dosages for up to two months as part of a tapering regime, before being given placebo pills only.

Over the following year, 56 per cent of participants who stopped taking their antidepressants experienced a relapse, compared to 39 per cent of participants who kept taking them.

Of the 56 per cent who experienced relapse after discontinuation, only half then chose to return to an antidepressant prescribed by their clinician. The researchers say that some relapses, as well as possible withdrawal symptoms, might not have been severe enough for the person to decide they needed to return to their medication.

Those who discontinued their antidepressants were more likely to experience withdrawal symptoms, the research showed. Despite this, by the end of the study, 59 per cent of the discontinuation group were not taking antidepressants.

Many people can also stop their medication without relapsing, said Dr Lewis, “though at present we cannot identify who those people are.”

The study showed that 44 per cent of people in the discontinuation group did not relapse during the course of the trial, compared to 61 per cent of those who kept receiving medication.

“The research question here is really can we find out which people are benefitting and which people aren’t,” said Glyn Lewis, a professor of epidemiological psychiatry at UCL.

“We’re dealing with averages. We’d like to be able to identify those people, the 40 per cent who can come off their antidepressants without a relapse. But at the moment we can’t identify those people.”

Co-lead author Dr Louise Marston, of the UCL Institute of Epidemiology and Health Care, said: “We do not yet know why some people seem able to come off their antidepressants and some cannot, so further research may help us to predict who can stop antidepressants safely.”

The scientists said that some people would be more likely to benefit from a dual approach, combining antidepressants with cognitive behavioural and mindfulness-based therapies.

Prof Lewis added that “antidepressants are effective but, like many medications, are not ideal for everyone”, highlighting that 39 per cent of people who continued with their treatment still experienced a relapse. His colleagues warned that the drugs “do not guarantee wellbeing”.

Nonetheless, Prof Lewis said, “there has been concern of people being on antidepressants for years, even decades, and we haven’t known really known ... whether there was still a benefit for them.

“But what this study convincingly demonstrates is that, yes, there is a benefit for staying on long-term antidepressants.”

Dr Sameer Jauhar, a senior clinical lecturer in affective disorders and psychosis at King’s College London, who was not involved in the research, said it was “an important study” that “fills the evidence gap” on the long-term use of antidepressants and offers reassurance for clinicians prescribing the drugs.