Health organisations around the world recommend a form of psychotherapy, known as cognitive-behavioural therapy or CBT, for patients with schizophrenia. Now, however, the most extensive study ever undertaken into its effect on the symptoms of the disorder finds little impact, according to a team of international researchers.

One of the most common serious mental health conditions, schizophrenia is experienced by around 1 in 100 people. Along with other leading treatment guideline groups, the UK’s influential National Institute for Health and Care Excellence (NICE) has argued that CBT is effective, and they currently recommend it for all people with the disorder.

Keith Laws, professor of cognitive neuropsychology at the University of Hertfordshire said: “This study is a new meta-analysis of CBT in the treatment of schizophrenia. It is the most comprehensive study of its effect on symptoms ever undertaken – covering fifty randomised controlled trials published over the last twenty years.

“We even translated papers from foreign languages, such as Chinese – so our study covers everything worthy of examination.”

The study found only a small therapeutic effect of CBT on schizophrenic symptoms. This included the key “positive” symptoms such as delusions and hallucinations, which CBT was originally developed to target. However, Professor Laws continued: “Even this small effect disappeared when only studies where the assessors were blind were taken into account.”

Blind testing, where the investigators who make the assessments don’t know which group of patients had received the therapy or not, is routinely used in trials of medical treatment but has not always been employed in studies of CBT for schizophrenia.

This new research raises the question of whether CBT should continue to be recommended in clinical practice. “With this evidence, the current government policy which mandates this treatment for all patients with schizophrenia in England and Wales needs to be reconsidered”, said Professor Laws.