Childhood loneliness as a specific risk factor for adult psychiatric disorders

A translational neuroscience perspective on loneliness: Narrative review focusing on social interaction, illness and oxytocin

This review addresses key findings on loneliness from the social, neurobiological and clinical fields. From a translational perspective, results from studies in humans and animals are included, with a focus on social interaction, mental and physical illness and the role of oxytocin in loneliness. In terms of social interactions, lonely individuals tend to exhibit a range of abnormal behaviors based on dysfunctional social cognitions that make it difficult for them to form meaningful relationships. Neurobiologically, a link has been established between loneliness and the hypothalamic peptide hormone oxytocin. Since social interactions and especially social touch regulate oxytocin signaling, lonely individuals may have an oxytocin imbalance, which in turn affects their health and well-being. Clinically, loneliness is a predictor of physical and mental illness and leads to increased morbidity and mortality. There is evidence that psychopathology is both a cause and a consequence of loneliness. The final section of this review summarizes the findings from social, neurobiological and clinical perspectives to present a new model of the complex construct of loneliness.

Factors associated with chronic depressive symptoms across adolescence and young adulthood: a UK birth cohort study

AIMS

Identifying children and/or adolescents who are at highest risk for developing chronic depression is of utmost importance, so that we can develop more effective and targeted interventions to attenuate the risk trajectory of depression. To address this, the objective of this study was to identify young people with persistent depressive symptoms across adolescence and young adulthood and examine the prospective associations between factors and persistent depressive symptoms in young people.

METHODS

We used data from 6711 participants in the Avon Longitudinal Study of Parents and Children. Depressive symptoms were assessed at 12.5, 13.5, 16, 17.5, 21 and 22 years with the Short Mood and Feelings Questionnaire, and we further examined the influence of multiple biological, psychological and social factors in explaining chronic depressive symptoms.

RESULTS

Using latent class growth analysis, we identified four trajectories of depressive symptoms: persistent high, persistent low, persistent moderate and increasing high. After applying several logistic regression models, we found that loneliness and feeling less connected at school were the most relevant factors for chronic course of depressive symptoms.

CONCLUSIONS

Our findings contribute with the identification of those children who are at highest risk for developing chronic depressive symptoms.

The Association between Discrepancies in Parental Emotional Expressivity, Adolescent Loneliness and Depression: A Multi-Informant Study Using Response Surface Analysis

Incongruent perceptions of parental emotional expressivity between parents and adolescents may signify relational challenges, potentially impacting adolescents' socioemotional adjustment. Direct evidence is still lacking and father-adolescent discrepancies are overlooked. This study employed a multi-informant design to investigate whether both mother-adolescent and father-adolescent discrepancies in perceptions of parental expressivity are related to adolescents' mental well-being, specifically focusing on loneliness and depression. Analyzing data from 681 families (mean age of adolescents = 15.5 years old, 51.2% girls, 40% only-children) in China revealed that adolescents tended to perceive paternal and maternal emotional expressivity more negatively than their parents, particularly fathers. Polynomial regression and response surface analysis showed significant links between parent-adolescent congruence and incongruence and adolescent loneliness. (In)Congruence between adolescents and mothers or fathers predicted later adolescent depression, mediated by adolescent loneliness and varied by the dimension of emotional expressivity. These findings provide insights into the roles of mothers' and fathers' emotional expressivity in shaping children's mental well-being during adolescence.

Trajectories of Loneliness During Adolescence Predict Subsequent Symptoms of Depression and Positive Wellbeing

There is a need to identify the outcomes of changes in loneliness during adolescence, and to consider this within a multidimensional framework of loneliness. This study considered the effects of different trajectories of change in Isolation Loneliness and in Friendship Loneliness upon both positive wellbeing and symptoms of depression. To achieve this, 1782 (43% female; 12.92 years old at the start of the study, SD = 1.60) young people took part in a longitudinal study with four data points across 2 years. Four Isolation Loneliness trajectories and five Friendship Loneliness trajectories were identified. Youth who experienced low levels of Isolation Loneliness that subsequently increased appear to be at particular risk for poor outcomes. Similarly, initially high levels of Friendship Loneliness that decreased rapidly, or which began at a low level and only increased marginally, seem to also be a risk. Loneliness is a multi-dimensional construct and its development during adolescence impacts upon young people's depressive symptomatology and positive mental wellbeing.

Loneliness in adolescence and prescription of psychotropic drugs in adulthood: 23-year longitudinal population-based and registry study

BACKGROUND

The role of adolescent loneliness in adult mental health and prescriptions of psychotropic drugs remains underexplored.

AIMS

We aim to determine whether (a) experiencing loneliness in adolescence and (b) changes in loneliness from adolescence to adulthood are prospectively associated with prescriptions for a variety of psychotropic drugs in adulthood.

METHOD

We used data from a Norwegian population-based sample with 2602 participants, collected across four waves between 1992 and 2006. Loneliness was assessed at each wave, with survey data linked to medicinal drug prescription records from the Norwegian Prescription Database. We identified prescription histories of antipsychotics, mood stabilisers, antidepressants and benzodiazepines from 2007 to 2015, for each participant. We use latent growth curve analyses to model the relationship of adolescent loneliness and loneliness change from adolescence to adulthood, with subsequent psychotropic drugs prescription.

RESULTS

Adolescents with heightened loneliness, and adolescents whose loneliness increased into young adulthood, had a greater likelihood of being prescribed antipsychotics, mood stabilisers and antidepressants in adulthood. These associations remained significant after adjustment for confounders such as sociodemographic characteristics, conduct problems, substance use and mental health problems.

CONCLUSIONS

Loneliness in adolescence and its adverse development over a span of 15 years was linked to higher risk of receiving prescriptions for antipsychotics, mood stabilisers and antidepressants later in life. The findings may indicate that loneliness increases the risk for developing psychotic disorders, bipolar disorders and major depression.

Loneliness and Risk of Parkinson Disease

Importance

Loneliness is associated with morbidity and mortality, including higher risk of neurodegenerative diseases. To our knowledge, no study has examined whether the association between loneliness and detrimental outcomes extends to Parkinson disease (PD).

Objective

To assess whether loneliness is associated with risk of incident PD and whether the association is independent of other risk factors or modified by age, sex, and genetic vulnerability.

Design, Setting, and Participants

This prospective cohort study included a population-based sample of UK Biobank participants aged 38 to 73 years with loneliness data and without a diagnosis of PD at baseline who were first assessed from March 13, 2006, to October 1, 2010, and followed up to October 9, 2021.

Exposure

Feeling lonely and covariates that are known risk factors for or prodromal features of PD.

Main Outcome and Measure

Incident PD was ascertained through UK National Health Service health records.

Results

Of 491 603 participants (mean [SD] age, 56.54 [8.09] years; 54.4% female), 2822 developed PD during the 15-year follow-up. Individuals who reported being lonely had a higher risk of PD (hazard ratio [HR], 1.37; 95% CI, 1.25-1.51), an association that remained after accounting for demographic factors, socioeconomic status, social isolation, PD polygenetic risk score, smoking, physical activity, body mass index, diabetes, hypertension, stroke, myocardial infarction, depression, and ever seeing a psychiatrist (fully adjusted model: HR 1.25; 95% CI, 1.12-1.39). The association between loneliness and incident PD was not moderated by sex (HR for interaction, 0.98; 95% CI, 95% CI, 0.81-1.18), age (HR for interaction, 0.99; 95% CI, 0.98-1.01), or polygenic risk score (HR for interaction, 0.93; 95% CI, 0.85-1.02). Contrary to expectations for a prodromal syndrome, when stratified by time, loneliness was not associated with risk for incident PD during the first 5 years (HR, 1.15; 95% CI, 0.91-1.45) but was associated with PD risk during the subsequent 10 years (HR, 1.32; 95% CI, 1.19-1.46).

Conclusions and Relevance

This large cohort study found that loneliness was associated with risk of incident PD across demographic groups and independent of depression and other prominent risk factors and genetic risk. The findings add to the evidence that loneliness is a substantial psychosocial determinant of health.

Spousal concordance in adverse childhood experiences and the association with depressive symptoms in middle-aged and older adults: findings across China, the US, and Europe

Background

Adverse childhood experiences (ACEs) are associated with higher depressive risks in adulthood. Whether respondents' ACEs are associated with their own depressive symptoms in adulthood and whether this association extends to their spouses' depressive symptoms remain unexplored.

Methods

Data were from China Health and Retirement Longitudinal Study (CHARLS), the Health and Retirement Study (HRS), and the Survey of Health, Ageing and Retirement in Europe (SHARE). ACEs were categorized into overall, intra-familial, and extra-familial ACEs. Correlations of couples' ACEs were calculated using Cramer's V and partial Spearman's correlation. Associations of respondents' ACEs with spousal depressive symptoms were assessed using logistic regression, and mediation analyses were conducted to explore the mediating role of respondents' depressive symptoms.

Results

Significant associations between husbands' ACEs and wives' depressive symptoms, with odds ratios (ORs) and 95% confidence intervals (CIs) of 2.09 (1.36-3.22) for 4 or more ACEs in CHARLS, and 1.25 (1.06-1.48) and 1.38 (1.06-1.79) for 2 or more ACEs in HRS and SHARE. However, wives' ACEs were associated with husbands' depressive symptoms only in CHARLS and SHARE. Findings in intra-familial and extra-familial ACEs were consistent with our main results. Additionally, respondents' depressive symptoms mediated more than 20% of the effect of respondents' ACEs on spousal depressive symptoms.

Conclusion

We found that ACEs were significantly correlated between couples. Respondents' ACEs were associated with spousal depressive symptoms, with respondents' depressive symptoms mediating the association. The bidirectional implications of ACEs on depressive symptoms should be considered within household and effective interventions are warranted.

Effectiveness of Psycho-Religious Sexuality Education upon Anger and Depression of Iranian Female Adolescents: The Relationship of Quality Family Relationships and Birth Order

Sexually active adolescents tend to have a wider range of psychosocial problems, including depression, anger, poor academic achievement, low self-esteem, and substance use. Developing a high-quality and curriculum-based comprehensive sexuality education (CSE) program is of great importance for adolescents following Iranian culture. Due to the lack of such an educational program, the purpose of this study was to investigate the effectiveness of psycho-religious CSE upon anger and depression of Iranian female adolescents, as well as the relationship of quality family relationships and birth order. The research design is quasi-experimental with pre-test and post-test with experimental and control groups. The statistical population of this study comprised all Iranian female adolescents aged 15 to 18 years in Mashhad who participated in this workshop voluntarily. For data collection, the Child and Adolescent Depression Inventory and Spielberger's State-Trait Anger Expression Inventory (STAXI) were used. SPSS 21 software and analysis of variance (ANOVA) and covariance (ANCOVA) were used for data analysis. The results showed that there was a significant difference in the mean difference between depression and anger in the control and experimental groups (p-Value < 0.05). The results also showed a significant relationship between birth order and the quality of family relationships on depression and anger. Psycho-religious-based SE can reduce depression and anger in female students. These findings can be used in planning educational interventions with a psycho-religious-based approach to reducing anger, depressive symptoms and dangerous sexual behaviors among adolescents.

Predictors of chronic loneliness during adolescence: a population-based cohort study

BACKGROUND

Adolescent loneliness is a growing public health issue owing to its adverse health impact. Although adolescent loneliness is common, its trajectories can show distinct patterns over time. However, there is limited knowledge regarding their determinants, particularly for chronic loneliness. We aimed to determine the predictors of loneliness trajectories across early-to-mid adolescence and examine their association with later suicidality.

METHODS

Data were collected from 3165 participants from the population-based Tokyo Teen Cohort. Participants reported their loneliness at 10, 12, 14, and 16 years. Loneliness trajectories were identified using latent class growth analysis. We examined the predictive role of bullying victimization and parental psychological distress at age 10 via a multinomial logistic regression. Sociodemographic and child-related factors (i.e., chronic health conditions and cognitive delay) were included as covariates. The association between the trajectories, self-harm, and suicidal ideation by age 16 was investigated using Poisson regression.

RESULTS

Four trajectories were identified: "consistently low" (2448, 77.3%), "moderate-decreasing" (185, 5.8%), "moderate-increasing" (508, 16.1%), and "consistently high" (24, 0.8%). Taking "consistently low" as a reference, experiences of bullying victimization predicted all the remaining trajectories [adjusted relative risk ratio 1.64, 95% confidence interval (CI) 1.18-2.28 for "moderate-decreasing," 1.88, 1.52-2.33 for "moderate-increasing," and 4.57, 1.97-10.59 for "consistently high"]. Parental psychological distress predicted the "moderate-increasing" (1.84, 1.25-2.71) and "consistently high" (5.07, 1.78-14.42) trajectories. The "consistently high" trajectory showed the greatest risk for self-harm and suicidal ideation (adjusted relative risk ratio 6.01, 95% CI 4.40-8.22; 2.48, 1.82-3.37, respectively); however, the "moderate-increasing" and "moderate-decreasing" trajectories were also at increased risk (moderate-increasing: 2.71, 2.23-3.30 for self-harm, 1.93, 1.69-2.19 for suicidal ideation; moderate-decreasing: 2.49, 1.91-3.26 for self-harm, 1.59, 1.33-1.91 for suicidal ideation).

CONCLUSIONS

Bullying victimization and parental psychological distress at age 10 were independent determinants of increased and chronic loneliness trajectories across early-to-mid adolescence. Compared with "consistently low," all other loneliness trajectories were associated with an increased risk of adolescent suicidality. Interventions targeting adolescent loneliness should include approaches to mitigate bullying and parental psychological distress. These strategies may help prevent adolescent suicidality.

Understanding the effect of loneliness on unemployment: propensity score matching

Background

Loneliness and unemployment are each detrimental to health and well-being. Recent evidence suggests a potential bidirectional relationship between loneliness and unemployment in working age individuals. As most existing research focuses on the outcomes of unemployment, this paper seeks to understand the impact of loneliness on unemployment, potential interaction with physical health, and assess bidirectionality in the working age population.

Methods

This study utilised data from waves 9 (2017–19) and 10 (2018–2020) of the Understanding Society UK Household Longitudinal Study. Nearest-neighbour probit propensity score matching with at least one match was used to infer causality by mimicking randomisation. Analysis was conducted in three steps: propensity score estimation; matching; and stratification. Propensity scores were estimated controlling for age, gender, ethnicity, education, marital status, household composition, number of own children in household and region. Findings were confirmed in panel data random effect models, and heterogeneous treatment effects assessed by the matching-smoothing method.

Results

Experience of loneliness in at least one wave increased the probability of being unemployed in wave 10 by 17.5 [95%CI: 14.8, 20.2] percentage points. Subgroup analysis revealed a greater effect from sustained than transitory loneliness. Further exploratory analysis identified a positive average treatment effect, of smaller magnitude, for unemployment on loneliness suggesting bidirectionality in the relationship. The impact of loneliness on unemployment was further exacerbated by interaction with physical health.

Conclusions

This is the first study to directly consider the potentially bidirectional relationship between loneliness and unemployment through analysis of longitudinal data from a representative sample of the working age population. Findings reinforce the need for greater recognition of wider societal impacts of loneliness. Given the persisting and potentially scarring effects of both loneliness and unemployment on health and the economy, prevention of both experiences is key. Decreased loneliness could mitigate unemployment, and employment abate loneliness, which may in turn relate positively to other factors including health and quality of life. Thus, particular attention should be paid to loneliness with additional support from employers and government to improve health and well-being.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13107-x.

Loneliness and the onset of new mental health problems in the general population

PURPOSE

Loneliness is associated with poor health including premature mortality. There are cross-sectional associations with depression, anxiety, psychosis, and other mental health outcomes. However, it is not known whether loneliness is causally linked with the new onset of mental health problems in the general population. Longitudinal studies are key to understanding this relationship. We synthesized evidence from longitudinal studies investigating the relationship between loneliness and new onset of mental health problems, in the general population.

METHOD

We systematically searched six electronic databases, unpublished sources, and hand-searched references, up to August 2021. We conducted a meta-analysis of eight independent cohorts and narrative synthesis of the remaining studies.

RESULTS

We included 32 studies, of which the majority focused on depression. Our narrative synthesis found most studies show loneliness at baseline which is associated with the subsequent new onset of depression. The few studies on anxiety and self-harm also showed a positive association. Our meta-analysis found a pooled adjusted odds ratio of 2.33 (95% CI 1.62-3.34) for risk of new onset depression in adults who were often lonely compared with people who were not often lonely. This should be interpreted with caution given evidence of heterogeneity.

CONCLUSION

Loneliness is a public mental health issue. There is growing evidence it is associated with the onset of depression and other common mental health problems. Future studies should explore its impact across the age range and in more diverse populations, look beyond depression, and explore the mechanisms involved with a view to better informing appropriate interventions.