How can you tell if a treatment works?

Sorry for the delay in writing this post – I had a bit of a break for finals and moving back home, but here I am with something I found interesting during revision: How can you tell if a treatment works?

At first glance, it might seem like this question can be easily answered, but it is not enough to give a group of a patients the treatment, and then see if their symptoms got better. For example, what if they would have got better anyway? Or it was something about the act of talking about their problems which caused them to feel better, not that the specific aspects of that therapy worked? I will now outline the method needed to conclude whether a psychological treatment is effective or not:

Randomised Controlled Trials (RCTS)

These are a type of experiment, known as the ‘gold standard’ for psychological experiments. The main feature is that participants are randomly assigned to different groups, for example, an experimental group, which receives the treatment, and a control group, who do not. Ideally, the patients in the control group are matched to patients in the experimental group e.g. same age, level of education etc. This is so that the effects of these other variables can be minimised, and so any difference in outcome can be attributed to the treatment. The control group is important to show that patients wouldn’t have got better anyway. For example, Mayou et al (2000) studied the effects of debriefing after trauma and found an objective drop in symptoms 3 years later. However, a control group who received no debrief had almost no symptoms 4 months after (see graph below). This shows the importance of a control group who received no intervention.

mayou et al

As well as finding out if a treatment is more beneficial than no treatment, RCTs can also be used to compare the effectiveness of different therapies for a psychological disorder. For example, Clark et al (1994) compared found cognitive therapy was the most effective treatment for panic disorder, compared to exposure therapy, applied relaxation, or imipramine (a drug treatment).


RCTs also include a follow-up some time after treatment, which enables researchers to tell if the treatment can cause long-term benefits. For example, in the Clark et al study shown above, you can see from the diagram that they carried out a follow up one year after treatment, and that patients in the cognitive therapy group still showed the largest reduction in panic symptoms.

RCTs are the method used to compare therapies, and in order to tell whether a treatment is effective, they need to feature:

  • A valid measure of symptoms at pre-treatment and post-treatment e.g. Body Sensations Interpretation Questionnaire (used by Clark et al to assess misinterpretations of body sensations in panic disorder patients).
  • Broad assessment e.g. patient and independent assessor. (Needed because patients have a tendency to report feeling better than they actually are to the person who’s been treating them).
  • Assess significant pre-treatment to post-treatment change.

It is important to tell whether a treatment works, as if it is shown to be effective, it is more likely to secure funding, and be used on patients within the NHS.

Thank you for reading, I’ll be able to get back into a routine with blogging again now my exams are over so check back soon for new posts!

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