Most people have experienced loneliness and have been able to overcome it to reconnect with other people. In the current review, we provide a life-span perspective on one component of the evolutionary theory of loneliness—a component we refer to as the reaffiliation motive (RAM). The RAM represents the motivation to reconnect with others that is triggered by perceived social isolation. Loneliness is often a transient experience because the RAM leads to reconnection, but sometimes this motivation can fail, leading to prolonged loneliness. We review evidence of how aspects of the RAM change across development and how these aspects can fail for different reasons across the life span. We conclude with a discussion of age-appropriate interventions that may help to alleviate prolonged loneliness.

The BBC Loneliness Experiment provided a unique opportunity to examine differences in the experience of lonelines across cultures, age, and gender, and the interaction between these factors. Using those data, we analysed the frequency of loneliness reported by 46,054 participants aged 16–99 years, living across 237 countries, islands, and territories, representing the full range of individualism-collectivism cultures, as defined by Hofstede (1997). Findings showed that loneliness increased with individualism, decreased with age, and was greater in men than in women. We also found that age, gender, and culture interacted to predict loneliness, although those interactions did not qualify the main effects, and simply accentuated them. We found the most vulnerable to loneliness were younger men living in individualistic cultures.

Background: Loneliness is common among youth and is associated with poor physical and mental health, and poor educational outcomes. To date, there have been no meta‐analyses of interventions aimed at reducing loneliness among young people. Methods: We conducted meta‐analyses of single group and randomised control trials (RCTs) of studies published between 1980 and 2019, which measured loneliness as an outcome in youth ages 25 years or younger. Moderators, including sample demographics and intervention characteristics, that might affect intervention success, were examined. Results: A total of 39 studies (14 single group and 25 RCTs) were included, and we found evidence that youth loneliness could be reduced via intervention. Moderator analysis – including intervention characteristics, study quality and sample demographics – was also examined. Conclusions: While interventions were shown to reduce loneliness among youth, the interventions included in the meta‐analyses often targeted youth viewed to be at risk – for example those with health concerns – and rarely did the interventions target youth who reported loneliness. There is also no indication of whether youth experienced chronic or transient loneliness. In future work, interventions should be designed specifically for loneliness, with universal programmes helping youth manage their transient feelings of loneliness, and targeted interventions for those suffering from chronic loneliness. There is also a need to look at socioeconomic and other risk factors outside the individual for targeted interventions. Key Practitioner Message: There have been no meta‐analyses that have evaluated the effect of interventions for reducing loneliness among children and adolescents. We found intervention programmes targeted at youth are successful at reducing loneliness. Future interventions should be designed specially with loneliness in mind, with (a) universal programmes to help youth manage their experiences of transient loneliness, and (b) targeted interventions for youth reporting chronic loneliness. They should also examine the longer‐term outcomes of the interventions. Future interventions should be designed, evaluated and then documented using guidelines on how to write up an intervention evaluation.

Aims: The present study investigates whether loneliness and social isolation are associated with poor physical and mental health among adolescents and young adults, and whether age and gender play a role in the associations of loneliness and social isolation with mental and physical health. Methods: This study used cross-sectional self-report data from the 2017 Danish Health and Morbidity Surveys titled ‘How are you?’ ( N = 19,890, M = 22.6 years). Results: Logistic regression analyses showed that loneliness and social isolation were independently associated with poor physical and mental health. Loneliness was associated with increased odds of asthma, migraine, osteoarthritis, rheumatoid arthritis, hypertension, slipped disc/back pain, tinnitus, long-term mental illness, depressive symptomatology, anxiety symptomatology and alcohol problems. Social isolation was associated with decreased odds of having migraine, osteoarthritis and alcohol problems, and an increased risk of long-term mental illness and depressive symptomatology. Small age and gender differences were detected. Conclusions: In adolescents and young adults, loneliness and social isolation were associated with poor mental health and loneliness with poor physical health. These findings highlight the need for targeted prevention and intervention initiatives to alleviate loneliness and social isolation.