“I keep reading that some therapies ‘work’ and others don’t. But how can I, as a patient, actually check what the evidence says about a treatment I’m considering?”
Metapsy is an open-source platform that collects and summarises the scientific evidence on psychological treatments for mental health conditions. Instead of reading hundreds of individual studies — or relying on whichever one happens to come up in a Google search — Metapsy lets you look at all the available evidence together, in one place.
Behind the scenes, researchers from around the world continuously gather the results of randomized controlled trials (the strongest type of study for testing whether a treatment works) and pool them into databases. These databases cover different mental health problems and are kept up to date as new studies are published.
Metapsy brings together what hundreds of trials say about a given therapy, so you don’t have to read them one by one.
Who Metapsy is for
Metapsy was originally built for researchers, and much of the documentation is quite technical. But one part of the platform has been specifically designed for a broader audience — including patients, family members, and anyone who wants to understand what therapy can realistically offer. That part is called the Effect Explorer.
The Effect Explorer: your starting point
The Metapsy Effect Explorer is a free online tool that lets you look up, in plain terms, how well psychological treatments work for eight common mental health conditions: depression, generalized anxiety disorder, panic disorder, social anxiety disorder, post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), specific phobia, and borderline personality disorder.
For each condition, the tool shows you the pooled response rate — that is, the proportion of people who improved substantially after therapy across all the studies that have been done — and compares it to the response rate in people who did not receive the therapy. This lets you see both how often therapy helps, and how much better it is than no treatment at all.
How to use it, step by step
Using the Effect Explorer does not require any statistical background. Click any step below for details.
1. Pick a condition
Choose the mental health problem you want to learn about — depression, PTSD, generalized anxiety disorder, OCD, and so on. The Effect Explorer currently covers eight common conditions.
2. Choose a treatment
You can look at specific types of therapy, such as cognitive behavior therapy, behavioral activation, interpersonal psychotherapy, or exposure-based therapy. Each of these has been studied in many trials, and the tool will pool them for you.
3. Optionally, filter further
You can narrow things down — for example, to adults only, to a specific format (individual, group, digital), or to trials comparing therapy against a particular control condition. Filtering lets you zoom in on the evidence most relevant to your situation.
4. Read the results
The tool will show you the percentage of people who responded to the treatment, the percentage who responded without it, and a visual display of the difference. It will also indicate how many studies and participants this estimate is based on — which matters, because estimates based on many studies are more reliable.
5. Download a report
If you want to take the information to a conversation with your clinician, you can generate a PDF report of what you looked at, including the studies it is based on. The report also contains a tracking ID so that the exact analysis can be reproduced later.
The Effect Explorer doesn’t tell you which treatment you should choose. It tells you what the evidence says on average, so that you and your clinician can make a better-informed decision together.
What Metapsy cannot do for you
It is worth being honest about the limits of the tool.
It describes averages, not individuals. If the Effect Explorer says that 42% of people with depression respond to therapy, that doesn’t mean you have a 42% chance. Your personal chances depend on many things the tool cannot see: your specific situation, the severity of your symptoms, your therapist, how well the approach fits you.
It cannot predict who will benefit from which therapy. The evidence currently does not allow us to say, for any one person, which therapy will work best. For now, that remains partly a matter of trial and error — and good conversation with your clinician.
It is not a substitute for professional advice. Metapsy gives you evidence. A clinician helps you apply that evidence to your life. Both are needed.
Plain-language answers to common questions
If clicking through a database feels like too much, there is also a simpler entry point. At metapsy.org/patients, we publish short, plain-language evidence summaries on the questions patients and clinicians most often ask about psychological treatments — questions like Does therapy really work? Is CBT the best treatment for depression? Can therapy have negative effects? What should I do if therapy isn’t helping me?
Each summary is written to be read in a few minutes, draws on the same underlying evidence as the Effect Explorer, and points to the studies behind the answer. If you want the conclusions without running the analyses yourself, start there.
Where to go next
If you want to explore the data directly, the easiest place to start is the Effect Explorer. Pick a condition you’re interested in and spend ten minutes clicking through — you’ll quickly get a feel for what the evidence looks like.
If you want to go deeper, the main Metapsy website links to the full databases, and the technical documentation explains how the data are collected and analysed. Those pages are more technical, but they are openly available to anyone who wants to see exactly where the numbers come from.
The goal of Metapsy is simple: to make the evidence on psychological treatments transparent and accessible, so that decisions about treatment — yours, your clinician’s, or your family’s — can be grounded in what we actually know.
Pim Cuijpers is professor emeritus of clinical psychology and scientific director of Metapsy. He has been involved in more than 1,100 scientific studies, mostly on psychological treatments of mental health problems. This is one of a series of evidence summaries in which Prof. Cuijpers tries to answer questions from patients and clinicians, based on what is known in science about treatments. The knowledge is mostly drawn from collective work of the Metapsy collaboration of at least 15 years. Do you have other questions you would like Prof. Cuijpers to discuss? Feel free to contact us.