DR RAJ PERSAUD MIND GAMES

What is the most researched drug worldwide? The answer, given that in trials for any drug there has to be a placebo comparison, is the placebo.

Most people think that if you get better despite the lack of clinical activity it must indicate you are a suggestible person. However, research by two teams of US psychologists produces a very different answer.

These findings are important because placebos have been described as one of the most powerful agents of symptom relief. It has even been argued that until the early 20th century, before the advent of proper clinical trials, the majority of treatments were little more than placebos.

It is still possible that the success of treatments is, in part, the result of placebos. Medical researchers suggest that placebo effects partially contribute to treatment success in virtually every area of medicine.

A placebo response occurs partly as a result of the reassurance we derive from finally getting treatment, combined with the authority of the doctor.

A paper due to be published in Medical Hypotheses journal argues that doctors and drug companies need to take personality into account more when prescribing or developing drugs.

It points out the lesser-known but equally common nocebo effect, where people develop side effects from an inert sugar pill.

There is even a personality type most prone to this, characterised by competitiveness and hostility. This may be because this kind of person finds it difficult to trust others, including doctors. Trust is needed to maximise the placebo effect.

Another study, in the Journal of Psychosomatic Research, finds further experimental confirmation that the placebo responder has a particular personality type. Psychologist Sarah Landry led a team of researchers from the University of Toledo in Ohio who found that optimistic people derive the greatest medical benefit from placebos.

Does the NHS concern itself with manipulating these powerful psychological effects? Not if the state of my waiting room is anything to go by.

Dr Raj Persaud is consultant psychiatrist at South London and Maudsley trust and Gresham professor for public understanding of psychiatry.