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Antidepressants may reduce anxiety more than symptoms of depression


An NIHR-funded trial has shown that one of the most common antidepressants, sertraline, reduces anxiety symptoms several weeks before it has an effect on depressive symptoms.

Published in The Lancet Psychiatry and led by researchers at University College London, the trial is the largest ever to compare an antidepressant to a placebo outside of trials funded by the pharmaceutical industry.

Participants taking sertraline didn’t show improvement in depressive symptoms such as low mood, loss of pleasure and poor concentration in the first six weeks. But there was weak evidence that these symptoms improved by 12 weeks.

There was however strong evidence that sertraline reduced generalised anxiety symptoms, with continued improvement from six weeks to 12 weeks, and led to better mental health-related quality of life.

The study was carried out in GP surgeries and involved 653 people in England, aged 18 to 74, with any depressive symptoms in the past two years. For each person taking part, doctors were uncertain whether to prescribe an antidepressant. Just over half of the participants met commonly used criteria for depression, 46% met criteria for generalised anxiety, and 30% met the criteria for both conditions.

Participants were randomly split into two groups, with one group given sertraline for 12 weeks, and the other placebo pills for 12 weeks.

“It appears that people taking the drug are feeling less anxious, so they feel better overall, even if their depressive symptoms were less affected,” said the study’s lead author, Dr
Gemma Lewis (UCL Psychiatry).

“We hope that we have cast new light on how antidepressants work, as they may be primarily affecting anxiety symptoms such as nervousness, worry and tension, and taking
longer to affect depressive symptoms.”

The study, funded by NIHR Programme Grants for Applied Research, provides useful modern context on how antidepressants may work.

Most large-scale trials of these drugs were conducted many years ago and only included patients in specialist mental health services. Antidepressants are now usually prescribed by GPs to a much broader group of patients.

The researchers say the findings could be useful to health professionals, as clinicians should be aware of which symptoms are likely to be treated by an antidepressant.

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