RecruitingInterventional

An international study of therapist-supported online cognitive behavioural therapy for the reduction of repetitive negative thought (overthinking, rumination, worry) in adults: the Calming Minds study

The Calming Minds study is an international research project looking at how an online talking therapy called Cognitive Behavioural Therapy (CBT) can help adults who often overthink, worry, or ruminate. These thoughts can make stress and low mood worse. This study wants to find out which specific parts of CBT work best to reduce these repetitive negative thoughts. By understanding this, we can make future treatments even better, simpler, and more widely available. Participants will receive one of 16 different versions of online CBT over 16 weeks, along with support from a therapist. The main goal is to improve mental health and well-being for those with, or at risk of, anxiety and depression.

At a glance

Status

Recruiting

Sponsor

University of Exeter

Enrolment target

1,692

Start

16 Apr 2026

Estimated completion

31 Dec 2027

Repetitive negative thought (overthinking, rumination, worry)

What is this study about?

Many of us sometimes find ourselves stuck in a cycle of overthinking, worrying, or going over things repeatedly in our minds – this is what we call 'repetitive negative thought'. While this is a common human experience, if it happens a lot, it can make stress and low mood much worse. It can even increase the chances of someone developing anxiety or depression.

We know that a type of talking therapy called Cognitive Behavioural Therapy (CBT) can be really helpful for reducing these kinds of thoughts. We've seen it work both in person and online. However, CBT has many different elements to it, and we don't fully understand which specific parts are the most powerful or 'active ingredients' in helping people. This study, called 'Calming Minds', aims to get to the bottom of this. We are comparing 16 slightly different versions of online CBT, each with varying combinations of its core components.

Our hope is that by pinpointing the most effective elements within CBT, we can make the treatment even better. This means future therapies could be more powerful, easier to understand, and more readily available to more people. Ultimately, this could lead to more effective ways to reduce repetitive negative thoughts, stress, low mood, and anxiety, helping many people improve their overall mental health and well-being.

Key takeaways

Targets overthinking, worrying, and rumination.
Compares different online CBT approaches to find the most effective elements.
Includes free online CBT and support from a trained therapist.
Requires a compatible smartphone and takes place over 16 weeks with a 12-month follow-up.
Aims to improve mental health and well-being for many people.
Excludes those with severe PTSD, substance abuse, bipolar disorder, psychosis, or recent changes in other treatments.

Who may be eligible?

This study is looking for adults aged 18 or older who experience a lot of repetitive negative thoughts, such as overthinking, worrying, or rumination. You'll also need access to a compatible smartphone (an recent iPhone or an Android phone with version 8.0 or higher) to take part.

There are some reasons why you wouldn't be able to join this particular study, as it might not be the right fit or could make it hard to see if the treatment works. For example, if you have severe Post-Traumatic Stress Disorder (PTSD), currently struggle with alcohol or substance abuse, or have been diagnosed with bipolar disorder or psychosis, you wouldn't be able to participate.

Also, if you're currently having other talking therapy, or have only recently started or changed the dose of antidepressant or anti-anxiety medication (less than six weeks ago), you wouldn't be able to take part. This is because we need to be sure that any changes in your thoughts are due to the CBT in the study, and not these other factors. If you can't join for any of these reasons, the study team can point you towards other helpful resources.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Do you often overthink, worry, or ruminate?
Do you have a recent iPhone (8 or newer) or an Android phone (version 8.0 or newer)?
Are you currently NOT having severe PTSD, struggling with substance abuse, or diagnosed with bipolar disorder or psychosis?
Are you NOT currently having other talking therapy or have you been on a stable dose of antidepressants/anti-anxiety medication for at least 6 weeks?

Answer every question to see your result.

What does participation involve?

If you join the study, you'll receive one of 16 different versions of online CBT. This will include six online therapy sessions that you'll complete at your own pace over a maximum of 16 weeks. You'll also have at least three video or phone calls with a trained therapist (called a Psychological Wellbeing Practitioner in the UK or a coach in the USA) during this time to support you through the online learning.

Before you start the therapy, you'll complete some questionnaires. You'll then fill out more questionnaires during the 16-week treatment period, and again at 16 weeks and 52 weeks after you first join the study. These questionnaires help us understand how you're feeling and whether the treatment is helping. The total duration of your involvement, including follow-up, would be about a year.

Potential risks and benefits

Participating in this study offers several potential benefits. Everyone who takes part will receive free online CBT, including six online sessions and at least three support sessions with a trained therapist. This can be very helpful for managing repetitive negative thoughts. You'll also gain information about other support services if they're relevant to you. By taking part, you’ll be contributing to important research that will help improve treatments for repetitive negative thoughts, ultimately benefiting many other people who struggle with anxiety and depression, and for some, you may learn to better understand and manage your own thoughts. While there are no known health risks from the questionnaires or therapy, completing them can be time-consuming. Some questionnaires ask about difficult emotions or experiences, and the CBT might encourage you to try new things, which could cause brief, mild upset, though this is usually no more than what you might experience in daily life. One questionnaire asks about suicidal thoughts, which can be distressing. However, study therapists are available to offer support if you become distressed, and can guide you to appropriate services if needed. You are always free to withdraw from the study at any time.

Locations (2)

University of Exeter
Approximate
Exeter, England
University of California, Los Angeles
Approximate
Los Angeles, United States of America

Common questions

What is 'repetitive negative thought'?

It's when you frequently overthink, worry a lot, or keep going over past events in your mind (rumination).

What is CBT?

CBT, or Cognitive Behavioural Therapy, is a type of talking therapy that helps you understand how your thoughts, feelings, and actions are connected, and how to change unhelpful patterns.

Do I need to pay to join?

No, all online CBT and therapist support provided as part of the study is completely free.

How long will I be involved in the study?

You'll have up to 16 weeks to complete the therapy sessions, and then follow-up questionnaires will be sent at 16 weeks and 52 weeks after you join.

Who is running this study?

The study is being run by the University of Exeter in the UK and the University of California, Los Angeles in the USA, with funding from the Wellcome Trust.

How to find out more

Katie Joyce

calming-minds-queries@exeter.ac.uk - Official trial record

Always speak to your GP or specialist before deciding to take part in a study.