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Social isolation and loneliness have been associated with poor health and increased risk for mortality, and inflammation might explain this link. We used data from the Danish TRIAGE Study of acutely admitted medical patients (N = 6,144, mean age 60 years), and from two population-representative birth cohorts: the New Zealand Dunedin Longitudinal Study (N = 881, age 45) and the UK Environmental Risk (E-Risk) Longitudinal Twin Study (N = 1448, age 18), to investigate associations of social isolation with three markers of systemic inflammation: C-reactive protein (CRP), interleukin-6 (IL-6), and a newer inflammation marker, soluble urokinase plasminogen activator receptor (suPAR), which is thought to index systemic chronic inflammation. In the TRIAGE Study, socially isolated patients (those living alone) had significantly higher median levels of suPAR (but not CRP or IL-6) compared with patients not living by themselves. Social isolation prospectively measured in childhood was longitudinally associated with higher CRP, IL-6, and suPAR levels in adulthood (at age 45 in the Dunedin Study and age 18 in the E-Risk Study), but only suPAR remained associated after controlling for covariates. Dunedin Study participants who reported loneliness at age 38 or age 45 had elevated suPAR at age 45. In contrast, E-Risk Study participants reporting loneliness at age 18 did not show any elevated markers of inflammation. In conclusion, social isolation was robustly associated with increased inflammation in adulthood, both in medical patients and in the general population. It was associated in particular with systemic chronic inflammation, evident from the consistently stronger associations with suPAR than other inflammation biomarkers., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: JEO is a named inventor on patents on suPAR as a prognostic biomarker. The patents are owned by Copenhagen University Hospital Amager and Hvidovre, Denmark, and is licensed to ViroGates A/S. JEO is a co-founder, shareholder, and CSO of ViroGates A/S. The remaining authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

The present study examined patterns of stability and change in loneliness across adolescence. Data were drawn from the Environmental Risk (E-Risk) Longitudinal Twin Study, a UK population-representative cohort of 2,232 individuals born in 1994 and 1995. Loneliness was assessed when participants were aged 12 and 18. Loneliness showed modest stability across these ages ( r = .25). Behavioral genetic modeling indicated that stability in loneliness was explained largely by genetic influences (66%), while change was explained by nonshared environmental effects (58%). Individuals who reported loneliness at both ages were broadly similar to individuals who only reported it at age 18, with both groups at elevated risk of mental health problems, physical health risk behaviors, and education and employment difficulties. Individuals who were lonely only at age 12 generally fared better; however, they were still more likely to finish school with lower qualifications. Positive family influences in childhood predicted reduced risk of loneliness at age 12, while negative peer experiences increased the risk. Together, the findings show that while early adolescent loneliness does not appear to exert a cumulative burden when it persists, it is nonetheless a risk for a range of concomitant impairments, some of which can endure.

Background: Loneliness co-occurs alongside many mental health problems and is associated with poorer treatment outcomes. It could therefore be a phenomenon of interest to clinicians as an indicator of generalised risk for psychopathology. The present study tested whether a short measure of loneliness can accurately classify individuals who are at increased risk of common mental health problems., Methods: Data were drawn from two nationally representative cohorts: the age-18 wave of the UK-based Environmental Risk (E-Risk) Longitudinal Twin Study and the age-38 wave of the New Zealand-based Dunedin Multidisciplinary Health and Development Study. In both cohorts, loneliness was assessed using the three-item UCLA Loneliness Scale, plus two stand-alone items about feeling alone and feeling lonely. Outcome measures consisted of diagnoses of depression and anxiety and self-reports of self-harm/suicide attempts, assessed via a structured interview., Results: ROC curve analysis showed that the Loneliness Scale had fair accuracy in classifying individuals meeting criteria for all three outcomes, with a cut-off score of 5 (on a scale from 3 to 9) having the strongest empirical support. Both of the stand-alone items showed modest sensitivity and specificity but were more limited in their flexibility. The findings were replicated across the two cohorts, indicating that they are applicable both to younger and older adults. In addition, the accuracy of the loneliness scale in detecting mental health problems was comparable to a measure of poor sleep quality, a phenomenon which is often included in screening tools for depression and anxiety., Conclusions: These findings indicate that a loneliness measure could have utility in mental health screening contexts, as well as in research.

The present study used a longitudinal and discordant twin design to explore in depth the developmental associations between victimization and loneliness from mid-childhood to young adulthood. The data were drawn from the Environmental Risk (E-Risk) Longitudinal Twin Study, a birth cohort of 2,232 individuals born in England and Wales during 1994–1995. Diverse forms of victimization were considered, differing across context, perpetrator, and timing of exposure. The results indicated that exposure to different forms of victimization was associated with loneliness in a dose–response manner. In childhood, bullying victimization was uniquely associated with loneliness, over and above concurrent psychopathology, social isolation, and genetic risk. Moreover, childhood bullying victimization continued to predict loneliness in young adulthood, even in the absence of ongoing victimization. Within-twin pair analyses further indicated that this longitudinal association was explained by genetic confounds. In adolescence, varied forms of victimization were correlated with young adult loneliness, with maltreatment, neglect, and cybervictimization remaining robust to controls for genetic confounds. These findings indicate that vulnerability to loneliness in victimized young people varies according to the specific form of victimization in question, and also to the developmental period in which it was experienced. [ABSTRACT FROM AUTHOR]

The present study used quantitative and qualitative methods to explore how lonely young people are seen from others' perspectives, in terms of their personality, behavior, and life circumstances. Data were drawn from the Environmental Risk Longitudinal Twin Study, a cohort of 2,232 individuals born in the U.K. in the mid-1990s. When participants were aged 18, they provided self-reports of loneliness, and informant ratings of loneliness were provided by interviewers, as well as participants' parents and siblings. Interviewers further provided Big Five personality ratings and detailed written notes in which they documented their perceptions of the participants and their reflections on the content of the interview. In the quantitative section of the article, regression analyses were used to examine the perceptibility of loneliness and how participants' loneliness related to their perceived personality traits. The informant ratings of participants' loneliness showed good agreement with self-reports. Furthermore, loneliness was associated with lower perceived conscientiousness, agreeableness, and extroversion and higher perceived neuroticism. Within-twin pair analyses indicated that these associations were partly explained by common underlying genetic influences. In the qualitative section of the study, the loneliest 5% of study participants (N = 108) were selected, and thematic analysis was applied to the study interviewers' notes about those participants. Three themes were identified and named: "uncomfortable in own skin," "clustering of risk," and "difficulties accessing social resources." These results add depth to the current conceptualization of loneliness and emphasize the complexity and intersectional nature of the circumstances severely lonely young adults live in. [ABSTRACT FROM AUTHOR]

We assessed genetic and environmental influences on social isolation across childhood and the overlap between social isolation and mental health symptoms including depression symptoms, conduct problems, and psychotic-like experiences from adolescence to young adulthood. Participants included 2,232 children from the Environmental Risk Longitudinal Twin Study. Social isolation was measured at ages 5, 7, 10, 12, and 18. A Cholesky decomposition was specified to estimate the genetic and environmental influences on social isolation across ages 5, 7, 10, and 12. An independent pathway model was used to assess additive genetic (A), shared environmental (C), and non-shared environmental (E) influences on the overlap between social isolation and mental health problems from age 12 to 18. Genetic and non-shared environmental influences accounted for half of the variance in childhood social isolation. Genetic influences contributed to the continuity of social isolation across childhood, while non-shared environmental influences were age-specific. The longitudinal overlap between social isolation and mental health symptoms was largely explained by genetic influences for depression symptoms (r = 0.15–0.24: 82–84% A, 11–12% C, and 5–6% E) and psychotic-like experiences (r = 0.13–0.15: 81–91% A, 0–8% C, and 9–11% E) but not conduct problems (r = 0.13–0.16; 0–42% A, 42–81% C, 16–24% E). Our findings emphasise that rather than a risk factor or an outcome, social isolation is aetiologically intertwined with the experience of poor mental health. An integrative assessment of social isolation could be a helpful indicator of underlying mental health symptoms in young people. [ABSTRACT FROM AUTHOR]