A total of 439 patients, who were considered to have recovered from their symptoms following therapy on the NHS, took part in the study. Over half of these were found to have suffered a relapse event, with up to 79 per cent of events occurring within the first six months after treatment.
The study, published in Behaviour Research and Therapy, was conducted by a team of NHS clinicians and scientists from the Universities of York, Sheffield, Huddersfield and Trier.
Dr Shehzad Ali, from the University of York's Department of Health Sciences, said: "Our research highlights that, under the current system, some patients are being discharged too soon. As a result, patients who have low levels of depression at the time of discharge are more likely to relapse within a few months."
Participants in the study were in contact with researchers on a monthly basis for 12 months after treatment to monitor their wellbeing and to quantify the percentage of cases that relapsed. Patients with residual depression symptoms at the end of treatment were twice as likely to relapse.
Dr Jaime Delgadillo, from the University of Sheffield, said: "These findings underline the importance of monitoring patients' wellbeing for at least six months after treatment and offering adequate support to ensure they stay well. We argue that relapse prevention is a crucial but often neglected aspect of psychological care in the NHS.
"Incomplete or insufficient treatment also costs the NHS, as patients who relapse often need further care or support."
According to a report in 2016 from the independent Mental Health Taskforce to the NHS, poor mental health carries an economic and social cost of £105 billion a year in England. In total, £9.2 billion is spent every year by the NHS on mental health support and services.
Depression and anxiety are highly common and often disabling mental health problems, experienced by one in six adults in the UK.
Available treatments in the NHS include medication and psychological therapy. The most widely available form of psychological care for these conditions is known as Low intensity Cognitive Behavioural Therapy (LiCBT), which is a brief and simplified adaptation of a treatment called Cognitive Behavioural Therapy (CBT).
LiCBT involves weekly contact with a mental health professional who guides patients on how to look after their mental health and typically lasts under two months. LiCBT has been found to lead to short-term improvement of depression and anxiety in previous studies, although there is as still limited evidence about its long-term effectiveness after treatment.
Article: How durable is the effect of low intensity CBT for depression and anxiety? Remission and relapse in a longitudinal cohort study, Shehzad Ali et al., Behaviour Research and Therapy, doi: 10.1016/j.brat.2017.04.006, published online 18 April 2017.