Of several psychological interventions, multi-component positive psychological interventions (PPIs) and mindfulness-based interventions are consistently associated with improvement in mental wellbeing, according to a systematic review and meta-analysis published in Nature Human Behavior.

After searching several databases, the researchers identified 393 randomized controlled trials with 53,288 total participants that evaluated a psychological or behavioral intervention in comparison to assessment only or waitlist, control group participants, or treatment-as-usual. They needed to use at least 1 validated measure of mental wellbeing. Studies of individuals with cognitive impairment were excluded.

Most studies used subjective wellbeing outcome measures and those measures reflected general mental wellbeing scores. The highest significant effect sizes were in mindfulness (g ranging between 0.35 and 0.65) and multi-component PPIs (g ranging between 0.36 and 0.62, all P =.000). Other multi-theoretical interventions (g=0.26, P =.000), singular PPIs (g=0.20, P =.000), and reminiscence interventions (g=0.34, P =.000) also significantly improved subjective wellbeing in the general population.

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Mindfulness-based interventions led to significant small-to-moderate wellbeing improvements for the general population and physically ill populations and a moderate-to-large effect in mentally ill populations.

Studies of multi-component PPI indicated significant benefits on wellbeing in the general population with small effect sizes and high-quality evidence. They showed moderate effect sizes on physically ill cohorts and small but significant effect sizes for general and mentally ill populations.

Cognitive therapy- or CBT-based interventions led to significant improvements in the wellbeing for cohorts of individuals with mental illness (g=0.40, P =.000), but not the physically ill or individuals of the general population.

Multi-theoretical interventions were helpful for general populations and physically ill individuals (g=0.24, P =.002), with insufficient evidence regarding individuals with mental illness.

Singular PPIs had small, significant on wellbeing in the general population. The studies, overall, had high evidence quality. They also appeared to benefit mentally ill populations, but the evidence quality was very low.

Studies of reminiscence interventions indicated significant benefits for the general population with a small positive effect on individuals with mental illness, though evidence quality was low for both.

ACT interventions produced a small to moderate effect on overall wellbeing in the general population, with low evidence quality due to risk of bias and wide confidence interval spans. Compassion interventions, which had low evidence quality, had an insignificant effect in the general population (P =.014). Expressive writing interventions, which also had low evidence quality, did not have significant benefit for the general population (P =.019). Both methods had insufficient studies of mentally and physically ill populations to be included in the meta-analysis.

While evidence for the efficacy of mindfulness and both types of PPI was high in the general population, the majority of studies were judged to have low or very low evidence quality. Psychological wellbeing could only be included in a meta-analysis examining the impact of multi-component PPIs, showing a small-to-moderate significant effect (g=0.44, P =.002).

Limitations of the study include the inconsistency of reporting standards of research published regarding wellbeing, the exclusion of Masters or PhD theses and grey literature, and the exclusion of direct comparisons of different types of psychological interventions.


van Agteren J, Iasiello M, Lo L, et al. A systematic review and meta-analysis of psychological interventions to improve mental wellbeing. Nat Hum Behav. Published online April 19, 2021. doi:10.1038/s41562-021-01093-w