Although correlates of mental wellbeing have been extensively studied, relatively little is known about how to effectively raise mental wellbeing in local communities by means of intervention. We conduct a randomised controlled trial of the "Exploring What Matters" course, a scalable social-psychological intervention aimed at raising general adult population mental wellbeing and pro-sociality. The manualised course is run by non-expert volunteers in their local communities and to date has been conducted in more than 26 countries around the world. We find that it has strong, positive causal effects on participants' self-reported subjective wellbeing (life satisfaction increases by about 63% of a standard deviation) and pro-sociality (social trust increases by about 53% of a standard deviation) while reducing measures of mental ill health (PHQ-9 and GAD-7 decrease by about 50% and 42% of a standard deviation, respectively). Impacts seem to be sustained two months post-treatment. We complement self-reported outcomes with biomarkers collected through saliva samples, including cortisol and a range of cytokines involved in inflammatory response. These move consistently into the hypothesised direction but are noisy and do not reach statistical significance at conventional levels.
Note that it's not peer-reviewed, but I didn't see any red flags when looking through the paper. If the estimates in the paper turn out to be reliable, it has external validity, persistence, etc., this seems like a surprisingly impactful and scalable intervention.
TL;DR: Big, if true.
Course material can be found here.
I don't have much time to spend on this, but here are a few thoughts based on a quick skim of the paper.
The study was done by some of the world's leading experts in wellbeing and the study design seems okay-ish ('waitlist randomisation'). The main concern with internal validity, which the authors acknowledge, is that changes in the biomarkers, while mostly heading in the right direction, were far from statistically significant. This could indicate that the effects reported on other measures were due to some factor other than actual SWB improvement, e.g. social desirability bias. But biomarkers are not a great metric, and measures were taken to address these concerns, so I find it plausible that the effects in the study population were (nearly) as large as reported.
However:
- The participants were self-selected, largely from people who were already involved with Action for Happiness ("The charity aims to help people take action to create more happiness, with a focus on pro-social behaviour to bring happiness to others around them"), and largely in the UK. They also had to register online. It's unclear how useful it would be for other populations.
- It's quite an intensive program, involving weekly 2–2.5 hour group meetings with a trained facilitator two volunteer facilitators. ("Each of these sessions builds on a thematic question, for example, what matters in life, how to find meaning at work, or how to build happier communities.") This may limit its scalability and accessibility to certain groups.
- Follow-up was only for 2 months, the duration of the course itself. (This limitation seems to be due to the study design: the control group was people taking the course 8 weeks later.)
- The effect sizes for depression and anxiety were smaller than for CBT, so it may still not be the best option for mental health treatment (though the CBT studies were done in populations with a diagnosed mental disorder, so direct comparison is hard; and subgroup analyses showed that people with lower baseline wellbeing benefited most from the program).
- For clarity, the average effect size for life satisfaction was about 1 point on a 10-point scale. This is good compared to most wellbeing interventions, but that might say more about how ineffective most other interventions are than about how good this one is.
So at the risk of sounding too negative: it's hardly surprising that people who are motivated enough to sign up for and attend a course designed to make them happier do in fact feel a bit happier while taking the course. It seems important to find out how long these effects endure, and whether the course is suitable for a broader range of people.
Thanks - I missed that on my skim. But the "extended" follow-up is only for another two months. It does seem to indicate that effects persist for at least that period, without any trend towards baseline, which is promising (though without a control group the counterfactual is impossible to establish with confidence). I wonder why they didn't continue to collect data beyond this period.