A long-running, nationally representative twin study has concluded that loneliness in childhood and social isolation independently forecast mental health, well-being and employment prospects in young adulthood, and that loneliness does not appear to help isolated youths reconnect. The Environmental Risk Longitudinal Twin Study, led by researchers at King’s College London, followed more than two thousand twins from England and Wales to age 18, collecting data at ages 12 and 18.
In the researchers’ framework, social isolation is the objective absence of supportive relationships, while loneliness is the subjective sense that one’s social connections are unsatisfactory. A child can be surrounded by peers and still feel lonely, or be alone without feeling lonely, the study notes.
The paper situates its findings in a broader debate. Some evolutionary theories have framed loneliness as a useful alarm bell that nudges people to seek company, while a German study of older adults suggested loneliness and isolation can interact to affect mortality. The new study directly tests these ideas as youths transition into adulthood.
“Although there is a large body of evidence that loneliness has negative consequences for health and wellbeing, some influential theories suggest that loneliness also serves a useful purpose by motivating socially isolated people to rebuild their social connections,” said Bridget T. Bryan, a research fellow at King’s College London’s Social, Genetic & Developmental Psychiatry Centre. “They argue that loneliness is a bit like hunger: an uncomfortable experience that signals to us that a basic need isn’t being met and motivates us to act on it. In this case, loneliness signals that we have unmet social needs, and pushes us to connect with others.”
She emphasised that few studies have tested whether this plays out in the long term, partly because loneliness and social isolation are rarely measured together. “To address this gap, the researchers designed a study to track whether loneliness actually helps isolated children reconnect over time, and whether facing both loneliness and isolation simultaneously creates a magnified penalty for a person’s future well-being. “We also wanted to better understand how loneliness and isolation work together and separately to shape a young person’s health, wellbeing, education and employment as they grow up,” she added.
The team used data from the Environmental Risk Longitudinal Twin Study, which follows 2,232 twins born in England and Wales in 1994 and 1995. The sample is nationally representative, spanning a range of socioeconomic backgrounds, and consists of 49% male and 90% White participants. Data were gathered at two developmental stages: age 12 and age 18. At 12, mothers and teachers rated social isolation, and the children self-reported loneliness. At 18, participants self-reported loneliness and social isolation, assessed by access to supportive relationships with family and friends.
When outcomes were assessed at age 18, the researchers tracked a broad array of mental health indicators, well-being, sleep quality, health behaviours such as smoking and alcohol use, and socioeconomic measures including educational achievement, employability and whether participants were out of education and out of work.
The study found that loneliness and social isolation reinforce one another over time, rather than compensating for each other. “Children who felt lonely at age 12 tended to be more socially isolated at age 18, and this effect was about twice as strong as the reverse, where children who were socially isolated at age 12 reported higher levels of loneliness as young adults.”
This pattern does not support the theory that loneliness serves as a helpful alarm signal. Isolated children who experienced high loneliness went on to experience high levels of social isolation as young adults, just like their peers who were isolated but not lonely. “Rather than assuming these children will find their own way through it, our findings suggest loneliness and isolation may need to be tackled directly,” Bryan noted.
The researchers also found that loneliness and isolation at age 12 independently predicted poorer mental health, poorer well-being and worse socioeconomic standing at age 18. While most mental health links persisted after accounting for childhood mental health and personality, isolation’s link to depression and loneliness’s link to anxiety disappeared when these factors were considered. However, childhood social isolation remained linked to every future socioeconomic outcome. “Each mattered in its own right, not just because they tend to occur together,” Bryan explained.
The impact on education and employment proved particularly pronounced. “Social isolation was particularly important for education and employment outcomes – more socially isolated secondary school students went on to have fewer qualifications and be less employable in young adulthood than their less isolated peers,” the researcher continued. “The risk of becoming NEET (not in education, employment or training) was particularly striking: the most isolated children had around 2.4 times the odds of being NEET at 18, compared with their peers.”
Interestingly, the researchers did not find evidence of a compounded penalty. Young people who were both highly lonely and highly isolated faced similar levels of mental health and socioeconomic difficulties as those experiencing only one of the issues. The authors described this as a potential ceiling effect.
Nevertheless, the sheer scale of the isolation effect stood out. “What surprised us most was the strength of the association between social isolation and poor education and employment outcomes,” Bryan said. “We didn’t expect it to be quite this strong – two to three times stronger than for other well-established risk factors, like childhood depression or anxiety.”
The findings carry potential policy implications, particularly around youth employment. Bryan remarked that the results suggest social isolation may be a more powerful driver of future education and employment prospects than commonly acknowledged risk factors, even as policy attention focuses on skills and job opportunities.
As with all research, the study has limitations. Loneliness and social isolation were measured only at two points six years apart, leaving open the question of how shorter episodes of loneliness might influence outcomes. The researchers also used different measurement tools at ages 12 and 18 to reflect developmental changes, which complicates direct comparisons over time. The twin design may also limit generalisability to non-twin populations.
Looking ahead, the team hopes to identify the mechanisms behind the apparent failure of loneliness to help lonely youths reconnect and to extend the timeline to examine how these dynamics unfold in other life stages. “We’d like to better understand why loneliness doesn’t seem to help isolated children reconnect – for example, whether this is because they withdraw rather than reach out, or because other difficulties that often go along with loneliness (like social difficulties or anxiety) make attempts to reconnect less successful,” Bryan said. “Our study focused on childhood and adolescence, but loneliness and social isolation matter at all stages of life.”
The study, titled “Investigating the interplay of loneliness and social isolation across adolescence: Findings from a nationally representative longitudinal study,” lists Bridget T. Bryan, Katherine N. Thompson, Helen L. Fisher, Timothy Matthews, Barry Milne, and Louise Arseneault as authors.
