The KIND Challenge community intervention to reduce loneliness and social isolation, improve mental health, and neighbourhood relationships: an international randomized controlled trial

Abstract Purpose Loneliness and social isolation are risk factors for poor health, but few effective interventions are deployable at scale. This study was conducted to determine whether acts of kindness can reduce loneliness and social isolation, improve mental health, and neighbourhood social cohesion. Method Three randomized controlled trials (RCTs) were conducted in the USA, UK, and Australia, involving a total of 4284 individuals aged 18–90 years old, randomized to the KIND challenge intervention or a waitlist control group. Participants allocated to the intervention were asked to do at least one act of kindness per week within a four-week period. The primary outcome was loneliness and secondary outcomes included measures of social isolation, mental health, and neighbourhood social cohesion. Results There was a significant, albeit small, intervention effect after four weeks for reduced loneliness in the USA and the UK, but not for Australia. Relative to controls, KIND challenge participants also showed significantly reduced social isolation and social anxiety in the USA, and reduced stress in Australia. There was also reduced neighbourhood conflict in the USA, increased number of neighbourhood contacts in the USA and Australia, greater neighbourhood stability and feelings of neighbourhood importance in the UK, and better neighbourhood social relationships in Australia. Conclusion Promoting the provision of social support through small acts of kindness to neighbours has the potential to reduce loneliness, social isolation and social anxiety, and promote neighbourhood relationships, suggesting a potential strategy for public health campaigns. Trial registration Clinical Trials Registry. NCT04398472. Registered 21st May 2020.