Neurobiology of loneliness: a systematic review

Exome sequencing identifies protein-coding variants associated with loneliness and social isolation

BACKGROUND

Loneliness and social isolation are serious yet underappreciated public health problems, with their genetic underpinnings remaining largely unknown. We aimed to explore the role of protein-coding variants in the manifestation of loneliness and social isolation.

METHODS

We conducted the first exome-wide association analysis on loneliness and social isolation, utilizing 336,115 participants of white-British ancestry for loneliness and 346,115 for social isolation. Sensitivity analyses were performed to validate the genetic findings. We estimated the genetic burden heritability of loneliness and social isolation and provided biological insights into them.

RESULTS

We identified six novel risk genes (ANKRD12, RIPOR2, PTEN, ARL8B, NF1, and PIMREG) associated with loneliness and two (EDARADD and GIGYF1) with social isolation through analysis of rare coding variants. Brain-wide association analysis uncovered 47 associations between identified genes and brain structure phenotypes, many of which are critical for social processing and interaction. Phenome-wide association analysis established significant links between these genes and phenotypes across five categories, mostly blood biomarkers and cognitive measures.

LIMITATIONS

The measurements of loneliness and social isolation in UK Biobank are brief for these multi-layer social factors, some relevant aspects may be missed.

CONCLUSIONS

Our study revealed 13 risk genes associated with loneliness and 6 with social isolation, with the majority being novel discoveries. These findings advance our understanding of the genetic basis of these two traits. The study provides a foundation for future studies aimed at exploring the functional mechanisms of these genes and their potential implications for public health interventions targeting loneliness and social isolation.

The mediating effects of sleep quality in the relationship between loneliness and depression among middle-aged and older adults

Loneliness has long been recognized as a key predictor of depression in older adults, and both are related to sleep quality. However, to this day, less is known about whether sleep quality mediates their relationship. This study aimed to examine the relationship between loneliness, sleep quality, and depressive symptoms, and to further explore whether sleep quality mediates the relationship between loneliness and depressive symptoms. Using the random cluster sampling method, 1016 permanent residents aged 45 and above in Ankang City, Shaanxi Province were selected. The relationship between loneliness, sleep quality, and depressive symptoms was analyzed using binary logistic regression, and the mediating role of sleep quality between loneliness and depressive symptoms was analyzed using the PROCESS macro in SPSS 25.0 software. The average age of the participants in this study was 60.39 ± 8.50. Regression analyses showed that individuals with loneliness (OR 7.161, 95%CI: 4.889-10.490, P < 0.001) and those with poor sleep quality (OR 4.777, 95%CI: 3.301-6.913, P < 0.001) were more likely to experience depressive symptoms than individuals without loneliness and with good sleep quality. This study also found a significant mediating effect of sleep quality between loneliness and depressive symptoms [effect value = 0.066, bootstrap 95% CI: (0.037, 0.093)] with an effect size of 13.31%. Loneliness may lead to reduced sleep quality in individuals, which in turn may lead to or exacerbate depressive symptoms. Therefore, this study highlights the importance of assessing and improving sleep quality in lonely people.

Rethinking Depression-Beyond Neurotransmitters: An Integrated Psychoneuroendocrineimmunology Framework for Depression's Pathophysiology and Tailored Treatment

It is known that the effectiveness of drug treatment for depression, ammine deficit based, is largely unsatisfactory. In this review, we examine the proposal of a precision therapy has emerged and has received a strong push by the identification of the role of inflammation in depression. However, precision psychiatry risks being caught in the reductionist trap of searching for the molecular switch that resets the whole system and switches off the disease. This is an illusion since the human being is complex and depression is a systemic and variable disorder. In this study, we show the inadequacy of the reductionist paradigm, and, at the same time, illustrate the superiority of the systemic paradigm centered on psychoneuroendocrineimmunology (PNEI). According to the PNEI paradigm, depression is a disease of the whole human being, caused by different sources working together: psychological, biological, and behavioral. This means knowing the biological and psychological history of the subject, identifying relational and biological crisis factors, and building personalized treatments targeting those factors with the tools of medicine and psychology, which are not reducible to the combination of drugs and psychotherapy. Our proposal presents a paradigm shift that is both theoretical and practical, which enables clinicians to assess patients experiencing depression in a unified way and treat them in an integrated manner.

Neural Patterns of Social Pain in the Brain-Wide Representations Across Social Contexts

Empathy can be elicited by physiological pain, as well as in social contexts. Although physiological and different social contexts induce a strong subjective experience of empathy, the general and context-specific neural representations remain elusive. Here, it is combined fMRI with multivariate pattern analysis (MVPA) to establish neurofunctional models for social pain triggered by observing social exclusion and separation naturistic stimuli. The findings revealed that both social contexts engaged the empathy and social function networks. Notably, the intensity of pain empathy elicited by these two social stimuli does not significantly differentiate the neural representations of social exclusion and separation, suggesting context-specific neural representations underlying these experiences. Furthermore, this study established a model that traces the progression from physiological pain to social pain empathy. In conclusion, this study revealed the neural pathological foundations and interconnectedness of empathy induced by social and physiological stimuli and provide robust neuromarkers to precisely evaluate empathy across physiological and social domains.

Understanding Loneliness Through Analysis of Twitter and Reddit Data: Comparative Study

BACKGROUND

Loneliness is a global public health issue contributing to a variety of mental and physical health issues. It increases the risk of life-threatening conditions and contributes to the burden on the economy in terms of the number of productive days lost. Loneliness is a highly varied concept, which is associated with multiple factors.

OBJECTIVE

This study aimed to understand loneliness through a comparative analysis of loneliness data on Twitter and Reddit, which are popular social media platforms. These platforms differ in terms of their use, as Twitter allows only short posts, while Reddit allows long posts in a forum setting.

METHODS

We collected global data on loneliness in October 2022. Twitter posts containing the words "lonely," "loneliness," "alone," "solitude," and "isolation" were collected. Reddit posts were extracted in March 2023. Using natural language processing techniques (valence aware dictionary for sentiment reasoning [VADER] tool from the natural language toolkit [NLTK]), the study identified and extracted relevant keywords and phrases related to loneliness from user-generated content on both platforms. The study used both sentiment analysis and the number of occurrences of a topic. Quantitative analysis was performed to determine the number of occurrences of a topic in tweets and posts, and overall meaningful topics were reported under a category.

RESULTS

The extracted data were subjected to comparative analysis to identify common themes and trends related to loneliness across Twitter and Reddit. A total of 100,000 collected tweets and 10,000 unique Reddit posts, including comments, were analyzed. The results of the study revealed the relationships of various social, political, and personal-emotional themes with the expression of loneliness on social media. Both platforms showed similar patterns in terms of themes and categories of discussion in conjunction with loneliness-related content. Both Reddit and Twitter addressed loneliness, but they differed in terms of focus. Reddit discussions were predominantly centered on personal-emotional themes, with a higher occurrence of these topics. Twitter, while still emphasizing personal-emotional themes, included a broader range of categories. Both platforms aligned with psychological linguistic features related to the self-expression of mental health issues. The key difference was in the range of topics, with Twitter having a wider variety of topics and Reddit having more focus on personal-emotional aspects.

CONCLUSIONS

Reddit posts provide detailed insights into data about the expression of loneliness, although at the cost of the diversity of themes and categories, which can be inferred from the data. These insights can guide future research using social media data to understand loneliness. The findings provide the basis for further comparative investigation of the expression of loneliness on different social media platforms and online platforms.

Loneliness: A Scoping Review of Reviews From 2001 to 2023

The growing number of primary studies and reviews on loneliness, and the multidisciplinary efforts to comprehend this complex phenomenon from various perspectives, underscore the heightened recognition of its impact on individual and societal well-being and health. To comprehensively assess the size and scope of this research field, we conducted a scoping review of 35 English-language reviews of primary studies on loneliness, published between 2001 and 2023. Focusing specifically on psychological research, these reviews covered a total of N = 1,089 studies, which were conducted between 1986 and 2022. In addition to providing a broad overview of the structure of the field, the present scoping review aimed to explore the methodological landscape of loneliness research, including data collection, sample demographics, and measures, and to present key topics and evidence in the field. By deepening the understanding of loneliness and identifying data gaps and methodological challenges, our analyses provide critical insights for future research endeavors, thereby fostering advances in the field.

Functional connectivity induced by social cognition task predict individual differences in loneliness

Loneliness is intricately connected to social cognition, yet the precise brain mechanisms that underscore their relationship need further exploration. The present study employed a theory of mind processing task that engaged participants in assessing the trajectories of geometric shapes while undergoing fMRI scans. The comprehensive data pool encompassed loneliness assessments and brain imaging data from a cohort of 157 participants. Utilizing a machine learning approach, task-induced functional connectivity data was used to forecast individuals' loneliness scores. The findings unveil that specific patterns of task-induced alterations in brain functional connectivity hold a remarkable capability to anticipate loneliness scores. Further dissection of the data disclosed pivotal nodes, including the prefrontal cortex, temporoparietal junction, and amygdala, among other cerebral regions. Furthermore, functional connectivity among the social network, the default mode network, and somatomotor networks emerged as crucial factors in prediction. Brain regions contributed strongly in prediction are involved in a variety of social cognitive processes, including intention inference, empathy, and information integration. The results illuminate the association between brain functional connectivity induced by social cognition and loneliness, which enhance the comprehensive understanding of this complex emotional state and may have implications for its diagnosis and intervention.

The Impact of Stigma of Loneliness on Psychological Distress in Older Adults: The Chain Mediating Effect

OBJECTIVE

Loneliness and psychological distress are serious challenges for older adults to cope with and factors threatening life quality and happiness during their remaining years. Older people's attitudes and evaluations towards loneliness potentially affect psychological distress. Therefore, the current study aimed to examine the relationship between the stigma of loneliness and the psychological distress of older adults, further exploring the mediating effect of distress disclosure and loneliness.

METHODS

Conducted during February and March 2024, the questionnaire survey included 933 older adults (age 65-89) using the Stigma of Loneliness Scale (SLS), Distress Disclosure Index (DDI), UCLA Loneliness scale (ULS-6), and 6-item Kessler Psychological Distress Scale (K6). The obtained data were for descriptive statistical analysis, correlation analysis, and chain mediation model testing.

RESULTS

Stigma of loneliness was significantly positively correlated with loneliness and psychological distress (r=0.61-0.69, p<0.01), and distress disclosure was negatively correlated with stigma of loneliness, loneliness, and psychological distress (r=-0.37--0.48, p<0.01). Stigma of loneliness can not only directly affect the psychological distress of older adults (effect value=0.38), but also indirectly affect psychological distress through the mediating roles of distress disclosure (effect value=0.04) and loneliness (effect value=0.20), and the chain mediating effect of the two (effect value=0.05).

CONCLUSION

The study redounds to the in-depth understanding of the effect of the stigma of loneliness on psychological distress among older people and its internal mechanism. The research results contribute to theoretical reference in explaining the formation background of psychological distress among older cohorts, which intends to provide empirical evidence for intervention studies of reducing psychological distress.

The effect of grandparental care on social networking sites addiction in college: mediated by social anxiety and loneliness

OBJECTIVE

Grandparental care has become a common phenomenon, yet there is still limited research on the long-term psychological effects on children raised by their grandparents. This study aims to explore the impact of early grandparental care experiences on university students' social networking sites addiction, social anxiety, and loneliness.

METHODS

A random cluster sampling method was employed to select college students from a medical school in Jiangxi for a questionnaire survey. The study measured social networking sites addiction, social anxiety, and loneliness using the Bergen Social Media Addiction Scale (BSMAS), Interaction Anxiety Scale (IAS), and Loneliness Scale (ULS-6) respectively. Additionally, grandparental care was assessed through individual questions. Data analysis was conducted using mediated effects modeling.

RESULTS

In total, 4318 participants were recruited. 45.2% of participants were male and 54.8% were female. The study found a significant positive association between grandparental care experience and social networking sites addiction, social anxiety, and loneliness. The study revealed that social anxiety mediated 20.0% of the effect between grandparental care experiences and social networking sites addiction, while loneliness mediated 16.0% of this effect. Moreover, social anxiety and loneliness together mediated 12.0% of the chained effects between grandparental care experiences and social networking sites addiction.

CONCLUSION

Grandparental care has no direct impact on social networking sites addiction in adulthood. Social anxiety and loneliness play a mediating role between grandparental care and social networking sites addiction. Therefore, schools and families should prioritize efforts to enhance the physical and mental well-being of individuals receiving grandparental care. This can be achieved through targeted health promotion initiatives.

Development of a tool measuring various aspects of social detachment: The social detachment questionnaire for older population

BACKGROUND

Social detachment includes the subjective aspect "loneliness" and the objective aspect "social isolation," but tools to assess both dimensions are limited. This study aims to develop a questionnaire, the Social Detachment Questionnaire for Older Population (SDQO), that considers multiple dimensions of social detachment simultaneously.

METHODS

The study collected 600 valid samples from individuals aged 55 and above to examine the psychometric properties of the developed SDQO. Item analysis was conducted to assess the performance of each item, and exploratory factor analysis (EFA) was employed to analyze its initial structure and eliminate less ideal items. Subsequently, confirmatory factor analysis (CFA) was used to examine the model fit of the suggested structure by EFA, using different subsamples. Internal consistency, concurrent validity, and other analyses were also performed.

RESULTS

The original 27-item SDQO was reduced to 17 items after removing 4 questions in item analysis and 6 questions in EFA. The Cronbach's alpha for the 17-item version of SDQO was 0.80. Both EFA and CFA supported its 6-factor structure, with factors identified as community activities, loneliness, personal resources, leisure activities, friendship, and family resources. SDQO also demonstrated expected performance in concurrent validity.

CONCLUSION

The 17-item version of SDQO exhibited good reliability and validity, measuring various aspects of social detachment behavior, feelings, and resources. It holds value for future research applications.

Emotional Loneliness Is Related to Objective Cognitive Function in Older People With HIV in the Washington-Baltimore Area: A Cross-sectional Study

ABSTRACT

Loneliness confers a significant risk to numerous health outcomes, including cognitive impairment. This study assessed the relationship between loneliness subtypes (social and emotional) and cognition in older people with HIV (OPWH ≥ 50 years). Forty-two participants (STET = 61.5 years; 48% male; 74% Black) completed the six-item De Jong Gierveld Loneliness Scale and measures assessing objective and subjective cognition and depressive symptoms (Patient Health Questionnaire [PHQ-9]). Loneliness-cognition associations were examined using linear regression. Models were first adjusted for age, sex, race, and education, and then PHQ-9 score. Mean emotional and social loneliness scores were 1.24 ( SD = 1.22) and 1.21 ( SD = 1.14), respectively. After sociodemographic and PHQ-9 adjustment, emotional, but not social, loneliness was associated with poorer objective cognitive performance on processing speed (Digit Symbol) and executive function (CalCAP™). Findings have potential clinical importance for interventions that target specific loneliness subtypes to optimize cognitive performance in OPWH.

Predicting the Risk of Loneliness in Children and Adolescents: A Machine Learning Study

BACKGROUND

Loneliness is increasingly emerging as a significant public health problem in children and adolescents. Predicting loneliness and finding its risk factors in children and adolescents is lacking and necessary, and would greatly help determine intervention actions.

OBJECTIVE

This study aimed to find appropriate machine learning techniques to predict loneliness and its associated risk factors among schoolchildren.

METHODS

The data were collected from an ongoing prospective puberty cohort that was established in Chongqing, Southwest China. This study used 822 subjects (46.84% boys, age range: 11-16) followed in 2019. Five models, (a) random forest, (b) extreme gradient boosting (XGBoost), (c) logistic regression, (d) neural network, and (e) support vector machine were applied to predict loneliness. A total of 39 indicators were collected and 28 predictors were finally included for prediction after data pre-processing, including demographic, parental relationship, mental health, pubertal development, behaviors, and environmental factors. Model performance was determined by accuracy and AUC. Additionally, random forest and XGBoost were applied to identify the important factors. The XGBoost algorithm with SHAP was also used to interpret the results of our ML model.

RESULTS

All machine learning performed with favorable accuracy. Compared to random forest (AUC: 0.87 (95%CI: 0.80, 0.93)), logistic regression (AUC: 0.80 (95%CI: 0.70, 0.89)), neural network (AUC: 0.80 (95%CI: 0.71, 0.89)), and support vector machine (AUC: 0.79 (95%CI: 0.79, 0.89)), XGBoost algorithm had the highest AUC values 0.87 (95%CI: 0.80, 0.93) in the test set, although the difference was not significant between models. Peer communication, index of general affect, peer alienation, and internet addiction were the top four significant factors of loneliness in children and adolescents.

CONCLUSIONS

The results of this study suggest that machine learning has considerable potential to predict loneliness in children. This may be valuable for the early identification and intervention of loneliness.

Emotional reactivity and its impact on neural circuitry for attention-emotion interaction through regression-based machine learning model

Attentional paradigm can have a significant influence on the processing and experience of positive and negative emotions. Attentional mechanism refers to the tendency to selectively attend to a particular stimulus while ignoring others. In the context of emotions, individuals may exhibit attentional biases towards either positive or negative emotional stimuli. By directing attention towards a specific stimulus, individuals can modulate their emotional responses. When attention is directed towards negative or threatening stimuli, it can intensify negative emotions such as fear, sadness, anger and anxiety. Conversely, directing attention away from negative stimuli can reduce emotional reactivity and promote emotional regulation. Similarly, paying attention to positive stimuli can amplify positive emotions and facilitate positive emotional experiences. Attentional paradigms are also responsible for cognitive appraisal of emotional stimuli. The allocation of attention can shape how emotional stimuli are evaluated and categorized, influencing the subsequent emotional response. Since the relationship between attention and emotions is complex and can vary across individuals and contexts, it is important to understand the underlying cognitive neural dynamics of the same. Custom rank allocation model (CRAM) was used to decode the underlying neural dynamics of cognitive and emotional resource sharing through the non-significant EEG channels. During the main effect of global-local (GL), CRAM ranks and scores indicated that the EEG channels C4, PZ, OZ, and P4 were found to be the most non-significant channels. Similarly, CRAM ranks and scores of the interaction effects between global-local and positive emotion-negative emotion and the interaction effects between global-local and frequent-deviant-equal indicated midline central EEG channels CZ, PZ, FZ and OZ to be the main contributor of the cognitive and emotional resources to others. Understanding the dynamics of attention-emotion conflicts with reference to significant and non-significant channels is important to gain insights into the complex computational interplay between attention and emotion, leading to a deeper understanding of human cognition and emotion regulation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11571-024-10106-z.

[The relationship between obesity, social isolation, and mental health-results from the LIFE adult study]

BACKGROUND

Population-based studies on the relationship between social isolation and obesity, which also include younger adults, are still lacking in Germany. The aim of this study is to investigate the prevalence of social isolation in people with and without obesity. In addition, socially isolated people with and without obesity are examined with regard to socio-demographic and socio-economic factors as well as with regard to depressive symptoms.

METHODS

This study was based on baseline data from the LIFE Adult Study (18-79 years) from the 2011-2014 study period. The sample comprised n = 8350 participants. In addition to socio-demographic characteristics and socio-economic status (SES), data on social isolation (LSNS-6), depression (ADS), and body mass index (BMI) were collected. Evaluations were carried out using inferential statistical analyses.

RESULTS

Overall, 13.1% of the total sample were affected by social isolation. Participants with obesity (20.4%) had a significantly (p < 0.001) higher prevalence compared to those without obesity (11.4%). A better social integration was significantly associated with younger age (p < 0.001), female sex (p < 0.001), being married (and cohabiting) (p < 0.001), higher socioeconomic status (p < 0.001), and lower depressive symptoms (p < 0.001).

DISCUSSION

A higher BMI was not associated per se with poorer social integration. However, the present study showed that socially isolated people with obesity represent a special risk group for impaired mental health and had twice the prevalence of social isolation compared to those without obesity.

Short-Term Coupling Associations Between State Loneliness and Cognitive Performance in Daily Life Among Older Adults

OBJECTIVES

Despite extensive efforts to study individual differences in loneliness and neurocognitive health, little is known about how within-person changes in state loneliness relate to cognitive performance. This study addressed this gap by examining the association between within-person variation in state loneliness and cognitive performance assessed objectively in daily life.

METHODS

Participants were 313 community-dwelling older adults (70-90 years) who reported momentary feelings of loneliness and completed smartphone-based cognitive tests 5 times daily for 14 consecutive days. Mobile cognitive tests assess visual associative memory, processing speed, and spatial memory.

RESULTS

At the day level, average state loneliness levels were negatively related to cognitive performance on the same day and subsequent day. Consistent with the day-level analysis, momentary assessments of increased loneliness were consistently linked to worse cognitive performance on concurrent assessments. However, moments characterized by lower cognitive performance predicted higher levels of loneliness 3-4 hr later (next occasion), but not vice versa.

DISCUSSION

The findings suggest a prospective association between loneliness and cognitive performance, with higher daily loneliness negatively associated with cognitive performance on the same day and predicting worse performance the following day. Notably, within a single day, lower cognitive performance at a given moment predicted elevated loneliness later in the day. This highlights a complex, reciprocal relationship-loneliness predicting and being predicted by cognitive performance depending on timescale.

The impact of psychosocial adversity on brain and behaviour: an overview of existing knowledge and directions for future research

Environmental experiences play a critical role in shaping the structure and function of the brain. Its plasticity in response to different external stimuli has been the focus of research efforts for decades. In this review, we explore the effects of adversity on brain's structure and function and its implications for brain development, adaptation, and the emergence of mental health disorders. We are focusing on adverse events that emerge from the immediate surroundings of an individual, i.e., microenvironment. They include childhood maltreatment, peer victimisation, social isolation, affective loss, domestic conflict, and poverty. We also take into consideration exposure to environmental toxins. Converging evidence suggests that different types of adversity may share common underlying mechanisms while also exhibiting unique pathways. However, they are often studied in isolation, limiting our understanding of their combined effects and the interconnected nature of their impact. The integration of large, deep-phenotyping datasets and collaborative efforts can provide sufficient power to analyse high dimensional environmental profiles and advance the systematic mapping of neuronal mechanisms. This review provides a background for future research, highlighting the importance of understanding the cumulative impact of various adversities, through data-driven approaches and integrative multimodal analysis techniques.

Let me in: The neural correlates of inclusion motivation in loneliness

BACKGROUND

While it is well-established that humans possess an innate need for social belonging, the neural mechanisms underlying motivation for connection are still largely unknown. We propose that inclusion motivation - measured through the effort that individuals are willing to invest to be included in social interactions - may serve as one of the basic building blocks of social behavior and may change in lonely individuals.

METHODS

Following the screening of 303 participants, we scanned 30 low- and 28 high-loneliness individuals with functional magnetic resonance imaging while they performed the Active Inclusion Task (AIT). The AIT assesses the participants' levels of effort invested in influencing their inclusion during classic Cyberball conditions of fair play and exclusion.

RESULTS

High- compared to low-loneliness individuals showed higher urgency for inclusion, specifically during fair play, which correlated with higher activity in the right thalamus. Furthermore, in high-loneliness individuals, we found increased functional connectivity between the thalamus and the temporoparietal junction, putamen, and insula.

LIMITATIONS

Participants interacted with computerized avatars, reducing ecological validity. Additionally, although increasing inclusion in the task required action, the physical demand was not high. Additional limitations are discussed.

CONCLUSIONS

Inclusion motivation in loneliness is heightened during fair but not exclusionary interactions, and is linked to activity in brain regions implicated in appetitive behavior and social cognition. The findings indicate that lonely individuals may view threat in inclusionary interactions, prompting them to take action to regain connection. This suggests that inclusion motivation may help explain social difficulties in loneliness.

Biopsychosocial risk factors for subjective cognitive decline among older adults during the COVID-19 pandemic: a population-based study

OBJECTIVES

There have been concerns that the COVID-19 pandemic and the measures used to contain it impacted the cognitive health of older adults. We therefore examined the prevalence of subjective cognitive decline, and its associated risk factors and health consequencs, among dementia-free older adults 2 years into the pandemic in Switzerland.

STUDY DESIGN

Population-based cohort study.

METHODS

Prevalence of SCD was estimated using the cognitive complaint questionnaire administered to adults aged ≥65 years in June-September 2022 (Specchio-COVID19 cohort, N = 1414), and compared to prepandemic values from 2014 to 2018 (CoLaus|PsyCoLaus cohort, N = 1181). Associated risk factors and health consequences were assessed using logistic and/or linear regression.

RESULTS

Prevalence of SCD in 2022 (18.9% [95% CI, 16.2-21.9]) was comparable to prepandemic levels in 2014-2018 (19.5% [17.2-22.1]). Risk factors included established risks for dementia-namely health issues, health behaviours, and depressive symptoms. Self-reported post-COVID, perceived worsening of mental health since the start of the pandemic, less frequent social club attendance, and increased loneliness were also risk factors for SCD. In turn, SCD was associated with poorer objective cognitive performance, difficulty performing instrumental activities of daily living, greater risk of falls, and lower well-being at one-year follow-up.

CONCLUSIONS

While the overall prevalence of SCD in 2022 was comparable to prepandemic levels, we identified several pandemic-related risk factors for SCD, including perceived worsening of mental health and increased isolation since the start of the pandemic. These findings highlight the importance of mental health promotion strategies in reducing cognitive complaints and preventing cognitive decline.

Developing a brief telematic cognitive behavioral therapy for the treatment of social isolation in young adults

Objective

The present study aims to present a novel cognitive-behavioral intervention protocol focused on treating social isolation through telematic interaction, thus overcoming common barriers characteristic of face-to-face interventions.

Methods

We examined current literature about face-to-face and telematic psychotherapeutic interventions for the treatment of social isolation in early adulthood. Current evidence is mixed, suggesting the need to develop novel interventions focused on patients' cognitive functioning. Moreover, telematic interventions are promising candidates for overcoming common barriers intrinsic to the condition of social isolation.

Results

The present 8-session model inspired by cognitive behavioral theoretical models and cognitive interventions currently present in the literature is thought to help socially isolated adult patients reduce clinical symptoms associated with the condition and lead to a reduction in the avoidance of social situations, leading to an improvement of the quality of life.

Conclusion

We presented a telematic psychotherapeutic intervention aimed at helping adult patients suffering from social isolation who are unable to seek help from national health systems and face-to-face interventions, thus overcoming barriers intrinsic to social isolation. The present cognitive-behavioral treatment protocol has been developed in the context of a randomized clinical trial ongoing in Italy, aimed at implementing and testing the feasibility and effectiveness of multimodal digital interventions for treating social isolation.

Loneliness and brain rhythmic activity in resting state: an exploratory report

Recent studies using resting-state functional magnetic resonance imaging have shown that loneliness is associated with altered blood oxygenation in several brain regions. However, the relationship between loneliness and changes in neuronal rhythm activity in the brain remains unclear. To evaluate brain rhythm, we conducted an exploratory resting-state electroencephalogram (EEG) study of loneliness. We recorded resting-state EEG signals from 139 participants (94 women; mean age = 19.96 years) and analyzed power spectrum density (PSD) and functional connectivity (FC) in both the electrode and source spaces. The PSD analysis revealed significant correlations between loneliness scores and decreased beta-band powers, which may indicate negative emotion, attention, reward, and/or sensorimotor processing. The FC analysis revealed a trend of alpha-band FC associated with individuals' loneliness scores. These findings provide new insights into the neural basis of loneliness, which will facilitate the development of neurobiologically informed interventions for loneliness.

Loneliness Among Black/African American Adults Living with HIV: Sociodemographic and Psychosocial Correlates and Implications for Adherence

Loneliness, an emerging public health problem, is higher among people living with HIV and is associated with negative health outcomes. Black/African Americans have a high burden of HIV, and little is known about the characteristics of loneliness among Black adults living with HIV; therefore, this study sought to understand the sociodemographic and psychosocial correlates of Black adults living with HIV who are lonely and the implications of loneliness for their health outcomes. A sample of 304 Black adults living with HIV (73.8% sexual minority men) in Los Angeles County, CA, USA, completed the survey items assessing sociodemographic and psychosocial characteristics, social determinants of health, health outcomes, and loneliness. Antiretroviral therapy (ART) adherence was assessed electronically with the medication event monitoring system. Bivariate linear regressions analysis showed higher loneliness scores among those with higher levels of internalized HIV stigma, depression, unmet needs, and discrimination related to HIV serostatus, race, and sexual orientation. In addition, participants who were married or living with a partner, had stable housing, and reported receiving more social support had lower levels of loneliness. In multivariable regression models controlling for correlates of loneliness, loneliness was found to be a significant independent predictor of worse general physical health, worse general mental health, and greater depression. Loneliness was marginally associated with lower ART adherence. Findings suggest that Black adults living with HIV, who experience multiple intersectional stigmas, require targeted interventions and resources.

A prospective association between social isolation and cognitive performance among older adults in Europe: the role of loneliness and poor oral health

OBJECTIVES

The relationship between social isolation, loneliness, and tooth loss and cognition in older people is poorly understood. We examine how social isolation and cognitive performance are associated prospectively among older adults, as well as how tooth loss and loneliness are related to this association.

METHODS

Using data from 26,168 participants aged ≥50 from the Survey of Health, Ageing and Retirement in Europe (SHARE), we explored the association between social isolation, loneliness, tooth loss and cognition. We used bootstrapping with resampling strategies for testing a moderated mediating model.

RESULTS

Higher social isolation was associated with poorer cognitive performance (B = -0.20, 95% CI = -0.03, -0.01; R2 =0.60), an association mediated by the respondent's number of missing teeth (B = -0.001, 95% CI = -0.002, -0.001). Higher levels of social isolation were associated with a greater number of missing teeth, and a higher number of missing teeth was linked with poorer cognition. We also found that loneliness moderated the relationship between social isolation and both the number of missing teeth (B = -0.11, p  = 0.047) and cognitive performance.

CONCLUSION

In later life, social isolation and loneliness are associated with shoddy oral health and poor cognitive status. Clinicians and policymakers should be aware of both the association between social isolation and feelings of loneliness on dentition and oral health and their relationship to the cognitive status of older adults.

Psychosocial and biological pathways to aging : The role(s) of the behavioral and social sciences in geroscience

While the biological hallmarks of aging are widely recognized as fundamental mechanisms of biological aging, more recently, there have been calls within geroscience to understand the aging process more comprehensively by adding a perspective of the social hallmarks of aging. Social and behavioral factors, such as socioeconomic status, life events or behavior and beliefs can alter the aging process per se and act in complex interactions with biological pathways. In addition, underlying biological pathways have been proposed for various psychosocial concepts, such as views on age and relationship quality. The aim of the present article is to provide narrative insights into theoretical and empirical developments between social and behavioral gerontology and geroscience or biogerontology. This article focuses on the potential of an interdisciplinary aging research but it also sets out the critical perspective that social gerontology provides.

Effect of Socialization on Alzheimer's Disease During the COVID-19 Pandemic

Age is the strongest risk factor for Alzheimer's disease, a neurodegenerative disease where beta-amyloid plaques accumulate in the brain. Elderly individuals, especially those in nursing homes, were burdened by social isolation during the COVID-19 pandemic. The purpose of this literature review is to describe the effectiveness of social engagement and how combating isolation can have a neuroprotective effect on individuals at risk for Alzheimer's disease. We conducted a search in PubMed examining articles from 2010 to 2023 that discussed the impact of socialization on Alzheimer's disease, particularly during the COVID-19 pandemic. Our search terms were "Alzheimer's Disease + Socialization," "Social Isolation + Alzheimer's Disease," "Alzheimer's Disease + COVID-19," "COVID-19 + Social Isolation," and "Social Interventions + Alzheimer's Disease." Inclusion criteria consisted of patients ages 60 and older with Alzheimer's disease, mention of social isolation or engagement, and any relationship between COVID-19 and Alzheimer's disease. Exclusion criteria were defined as other dementias, non-social interventions, and the effects of different viruses on Alzheimer's disease. After the screening process, 30 articles were included, along with six articles that were suitable to the topic. Of the 36 total articles, 19 focused on an intervention involving socialization; eight explored the effect of social isolation during COVID-19 on patients with Alzheimer's disease; five articles examined social isolation as a risk factor for dementia; and four articles discussed the effect of socialization on Alzheimer's disease. A few studies reported that having a large social network can improve cognition and mood for patients with Alzheimer's disease. Studies reported that interventions such as volunteering, video calls, group art classes, animal interactions, and others produced positive outcomes in Alzheimer's patients, but not all were statistically significant. Our review found a consistent association between a socially integrated lifestyle and a decreased incidence of early-onset dementia. Although not all interventions were solely social, a strong social structure remained at the core of a healthy aging process.

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.

The Best of Two Worlds to Promote Healthy Cognitive Aging: Definition and Classification Approach of Hybrid Physical Training Interventions

A healthy lifestyle can be an important prerequisite to prevent or at least delay the onset of dementia. However, the large number of physically inactive adults underscores the need for developing and evaluating intervention approaches aimed at improving adherence to a physically active lifestyle. In this regard, hybrid physical training, which usually combines center- and home-based physical exercise sessions and has proven successful in rehabilitative settings, could offer a promising approach to preserving cognitive health in the aging population. Despite its potential, research in this area is limited as hybrid physical training interventions have been underused in promoting healthy cognitive aging. Furthermore, the absence of a universally accepted definition or a classification framework for hybrid physical training interventions poses a challenge to future progress in this direction. To address this gap, this article informs the reader about hybrid physical training by providing a definition and classification approach of different types, discussing their specific advantages and disadvantages, and offering recommendations for future research. Specifically, we focus on applying digital technologies to deliver home-based exercises, as their use holds significant potential for reaching underserved and marginalized groups, such as older adults with mobility impairments living in rural areas.

The functional connectivity of the right superior temporal gyrus is associated with psychological risk and resilience factors for suicidality

INTRODUCTION

Suicide attempters show increased activation in the right superior temporal gyrus (rSTG). Here, we investigated the rSTG functional connectivity (FC) to identify a functional network involved in suicidality and its associations with psychological suicidality risk and resilience factors.

METHODS

The resting state functional magnetic resonance imaging data of 151 healthy individuals from the Human Connectome Project Young Adult database were used to explore the FC of the rSTG with itself and with the rest of the brain. The correlation between the rSTG FC and loneliness and purpose in life scores was assessed with the NIH Toolbox. The effect of sex was also investigated.

RESULTS

The rSTG had a positive FC with bilateral cortical and subcortical regions, including frontal, temporal, parietal, occipital, limbic, and cerebellar regions, and a negative FC with the medulla oblongata. The FC of the rSTG with itself and with the left central operculum were associated with loneliness scores. The within rSTG FC was also negatively correlated with purpose in life scores, although at a trend level. We did not find any effect of sex on FC and its associations with psychological factors.

LIMITATIONS

The cross-sectional design, the limited age range, and the lack of measures of suicidality limit the generalizability of our findings.

CONCLUSIONS

The rSTG functional network is associated with loneliness and purpose in life. Together with the existing literature on suicide, this supports the idea that the neural activity of rSTG may contribute to suicidality by modulating risk and resilience factors associated with suicidality.

Charting Alzheimer's Disease and Dementia: Epidemiological Insights, Risk Factors and Prevention Pathways

Alzheimer's disease (AD), the most common cause of dementia, is a complex and multifactorial condition without cure at present. The latest treatments, based on anti-amyloid monoclonal antibodies, have only a modest effect in reducing the progression of cognitive decline in AD, whereas the possibility of preventing AD has become a crucial area of research. In fact, recent studies have observed a decrease in dementia incidence in developed regions such as the US and Europe. However, these trends have not been mirrored in non-Western countries (Japan or China), and the contributing factors of this reduction remain unclear. The Lancet Commission has delineated a constrained classification of 12 risk factors across different life stages. Nevertheless, the scientific literature has pointed to over 200 factors-including sociodemographic, medical, psychological, and sociocultural conditions-related to the development of dementia/AD. This narrative review aims to synthesize the risk/protective factors of dementia/AD. Essentially, we found that risk/protective factors vary between individuals and populations, complicating the creation of a unified prevention strategy. Moreover, dementia/AD explanatory mechanisms involve a diverse array of genetic and environmental factors that interact from the early stages of life. In the future, studies across different population-based cohorts are essential to validate risk/protective factors of dementia. This evidence would help develop public health policies to decrease the incidence of dementia.

Loneliness and Resting-State Functional Brain Connectivity Among Older Adults: A Proportional Correlation

OBJECTIVE

Loneliness reportedly increases the risk of dementia, especially Alzheimer's disease (AD). The authors' previous study demonstrated associations between loneliness and structural abnormalities observed in early-stage AD. The present study examined associations between the brain's functional characteristics and loneliness among older adults with concerns about cognitive decline.

METHODS

This single-center study included 43 participants (13 with amnestic mild cognitive impairment and 30 with normal cognition). Participants were assessed with the revised University of California Los Angeles (UCLA) Loneliness Scale and underwent resting-state functional MRI. Functional images were preprocessed with the CONN toolbox. The selected seeds were within brain regions reportedly associated with loneliness. One-sample general linear model analysis was performed to examine regressions of UCLA Loneliness Scale scores and functional connectivity between the seeds and regions of interest.

RESULTS

The revised UCLA Loneliness Scale scores were positively correlated with functional connectivity between the right hippocampus and left lateral parietal lobe and were negatively correlated with functional connectivity between the left amygdala and left frontal operculum and between the left amygdala and right supramarginal gyrus. Analyses were adjusted for age, sex, and education and scores on the Mini-Mental State Examination and Clinical Dementia Rating scale.

CONCLUSIONS

Loneliness was associated with abnormal function of the hippocampus, parts of the parietal lobe and frontal cortex, and the amygdala. These findings may suggest a possible correlation between loneliness and neurological changes associated with dementia.

Contributions of loneliness to cognitive impairment and dementia in older adults are independent of other risk factors and Alzheimer's pathology: a narrative review

Loneliness significantly contributes to cognitive impairment and dementia in older adults. Loneliness is a distressing feeling resulting from a perceived lack of social connection (i.e., a discrepancy between desired and actual social relationships), while social isolation is a related term that can be defined by number and type of social relationships. Importantly, loneliness is distinct from social isolation in that it is associated with a distressing self-perception. The primary focus of this narrative review is the impact of chronic loneliness on cognitive impairment and dementia among older adults. Loneliness has a significant association with many factors that are related to worse cognition, and therefore we include discussion on health, mental health, as well as the physiological effects of loneliness, neuropathology, and potential treatments. Loneliness has been shown to be related to development of dementia with a hazard ratio (HR) risk comparable to having a single APOE4 gene. The relationship of dementia to loneliness appears to be at least partially independent of other known dementia risk factors that are possibly associated with loneliness, such as depression, educational status, social isolation, and physical activity. Episodic memory is not consistently impacted by loneliness, which would be more typically impaired if the mild cognitive impairment (MCI) or dementia was due to Alzheimer's disease (AD) pathology. In addition, the several longitudinal studies that included neuropathology showed no evidence for a relationship between loneliness and AD neuropathology. Loneliness may decrease resilience, or produce greater cognitive change associated with the same level of AD neuropathology. Intervention strategies to decrease loneliness in older adults have been developed but need to consider key treatment targets beyond social isolation. Loneliness needs to be assessed in all studies of cognitive decline in elders, since it significantly contributes to the variance of cognitive function. It will be useful to better define the underlying mechanism of loneliness effects on cognition to determine if it is similar to other psychological factors related to excessive stress reactivity, such as neuroticism or even depression, which are also associated with cognitive decline. It is important from a health perspective to develop better strategies to decrease loneliness in older adults.

Loneliness as neurobehavioral issue in amyotrophic lateral sclerosis

OBJECTIVE

In elderly people loneliness represents a risk factor for dementia and may negatively impact on mental and physical health. The specific contribute of loneliness to cognitive and behavioral functioning have not yet been determined in amyotrophic lateral sclerosis (ALS). Our hypothesis was that loneliness may be related to motor dysfunction with a negative impact on cognitive and behavioral decline, possibly related to specific cortical involvement.

METHODS

In 200 ALS patients (ALSpts) and 50 healthy controls (HCs) we measured loneliness, mood, and quality of life (QoL). ALSpts underwent comprehensive clinical, genetic, and neuropsychological assessment to define phenotypes. Seventy-seven ALSpts performed 3T MRI scans to measure cortical thickness. Between-group, partial correlation and regression analyses were used to examined clinical, neuropsychological, and cortical signatures of loneliness.

RESULTS

Feelings of loneliness were documented in 38% of ALSpts (ALS/L+pts) and in 47% of HCs. In both groups loneliness was associated with anxiety (P < 0.001), depression (P ≤ 0.005), and poor QoL (P < 0.001). ALS/L+pts had similar motor dysfunctions and cognitive abilities than non-lonely ALSpts, but distinct behavioral profiles (P ≤ 0.005) and frontoparietal involvement (P < 0.05). Loneliness in ALS is related to behavioral changes, apathy, and emotional dysregulation (P < 0.001).

INTERPRETATION

Our cross-sectional study indicates that, in ALS, the satisfaction of social environment is associated with a sense of life well-being that is not limited to the motor status, proving instead that loneliness can impact on disease-related neurobehavioral changes with a possible flashback on brain architecture. This suggests that sociality could promote personal resilience against behavioral and affective decline in ALS.

Social Isolation, Brain Food Cue Processing, Eating Behaviors, and Mental Health Symptoms

Importance

Perceived social isolation is associated with negative health outcomes, including increased risk for altered eating behaviors, obesity, and psychological symptoms. However, the underlying neural mechanisms of these pathways are unknown.

Objective

To investigate the association of perceived social isolation with brain reactivity to food cues, altered eating behaviors, obesity, and mental health symptoms.

Design, Setting, and Participants

This cross-sectional, single-center study recruited healthy, premenopausal female participants from the Los Angeles, California, community from September 7, 2021, through February 27, 2023.

Exposure

Participants underwent functional magnetic resonance imaging while performing a food cue viewing task.

Main Outcomes and Measures

The main outcomes included brain reactivity to food cues, body composition, self-reported eating behaviors (food cravings, reward-based eating, food addiction, and maladaptive eating behaviors), and mental health symptoms (anxiety, depression, positive and negative affect, and psychological resilience).

Results

The study included 93 participants (mean [SD] age, 25.38 [7.07] years). Participants with higher perceived social isolation reported higher fat mass percentage, lower diet quality, increased maladaptive eating behaviors (cravings, reward-based eating, uncontrolled eating, and food addiction), and poor mental health (anxiety, depression, and psychological resilience). In whole-brain comparisons, the higher social isolation group showed altered brain reactivity to food cues in regions of the default mode, executive control, and visual attention networks. Isolation-related neural changes in response to sweet foods correlated with various altered eating behaviors and psychological symptoms. These altered brain responses mediated the connection between social isolation and maladaptive eating behaviors (β for indirect effect, 0.111; 95% CI, 0.013-0.210; P = .03), increased body fat composition (β, -0.141; 95% CI, -0.260 to -0.021; P = .02), and diminished positive affect (β, -0.089; 95% CI, -0.188 to 0.011; P = .09).

Conclusions and Relevance

These findings suggest that social isolation is associated with altered neural reactivity to food cues within specific brain regions responsible for processing internal appetite-related states and compromised executive control and attentional bias and motivation toward external food cues. These neural responses toward specific foods were associated with an increased risk for higher body fat composition, worsened maladaptive eating behaviors, and compromised mental health. These findings underscore the need for holistic mind-body-directed interventions that may mitigate the adverse health consequences of social isolation.

Validity of mental and physical stress models

Different stress models are employed to enhance our understanding of the underlying mechanisms and explore potential interventions. However, the utility of these models remains a critical concern, as their validities may be limited by the complexity of stress processes. Literature review revealed that both mental and physical stress models possess reasonable construct and criterion validities, respectively reflected in psychometrically assessed stress ratings and in activation of the sympathoadrenal system and the hypothalamic-pituitary-adrenal axis. The findings are less robust, though, in the pharmacological perturbations' domain, including such agents as adenosine or dobutamine. Likewise, stress models' convergent- and discriminant validity vary depending on the stressors' nature. Stress models share similarities, but also have important differences regarding their validities. Specific traits defined by the nature of the stressor stimulus should be taken into consideration when selecting stress models. Doing so can personalize prevention and treatment of stress-related antecedents, its acute processing, and chronic sequelae. Further work is warranted to refine stress models' validity and customize them so they commensurate diverse populations and circumstances.

Relationship between family function, self-perceived burden and loneliness in patients with type 2 diabetes mellitus: a cross-lagged analysis

AIMS

To explore the inter-predictive role and causal relationship between family functioning, self-perceived burden and loneliness in people with type 2 diabetes.

METHODS

In this study, patients with type 2 diabetes admitted to two tertiary care hospitals in China were selected for an 8-month follow-up, and the patients' scores on the Family Functioning, Self-perceived Burden, and Loneliness scales were measured repeatedly at three time periods: during hospitalisation (T1), 1 month after discharge (T2), and 3 months after discharge (T3).

RESULTS

The results showed that family function at the T1 time point had a negative predictive effect on self-perceived burden at the T2 time point, β = - 0.43, P = 0.005. Loneliness at the T1 time point had a positive predictive effect on self-perceived burden at the T2 time point, β = 0.08, P = 0.021. Unlike the pathway at time point T1, family functioning at time point T2 negatively predicted loneliness at time point T3, β = - 0.32, P = 0.013. Loneliness at time point T2 positively predicted family functioning at time point T3, β = 0.025, P = 0.013. Loneliness at time point T2 negatively predicted self-perceived burden at time point T3 (P = 0.011).

CONCLUSIONS

The results of the cross-lagged analysis show that there is a mutually predictive and moderating relationship between family functioning and loneliness in patients with type 2 diabetes. Loneliness can predict the level of self-perceived burden at the next time point.

Away from the herd: loneliness as a dysfunction of social alignment

The tendency of all humans to experience loneliness at some point in their lives implies that it serves an adaptive function. Building on biological theories of herding in animals, according to which collective movement emerges from local interactions that are based on principles of attraction, repulsion and alignment, we propose an approach that synthesizes these principles with theories of loneliness in humans. We present here the 'herding model of loneliness' that extends these principles into the psychological domain. We hold that these principles serve as basic building blocks of human interactions and propose that distorted attraction and repulsion tendencies may lead to inability to align properly with others, which may be a core component in loneliness emergence and perpetuation. We describe a neural model of herding in humans and suggest that loneliness may be associated with altered interactions between the gap/error detection, reward signaling, threat and observation-execution systems. The proposed model offers a framework to predict the behavior of lonely individuals and thus may inform intervention designs for reducing loneliness intensity.

Psychological and neurobiological mechanisms involved in the relationship between loneliness and cognitive decline in older adults

Loneliness, among older adults, is one of the risk factors for developing dementia. Still, little is known about the neurobiological and psychological conditions that link loneliness to cognitive decline. The current study investigated several research aims: First, it sought to identify neurobiological and psychological pathways that may account for the relationship between loneliness and decline across several cognitive domains. These pathways included depressive symptoms, total gray matter volume, and conditional analyses of pro-inflammatory cytokines and brain-derived neurotrophic factor (BDNF) expression. Second, it examined loneliness as a predictor of mild cognitive impairment (MCI) and Alzheimer's disease (AD). Third, it sought to determine whether the relationship between loneliness and cognitive decline is sex-specific in older adults. Longitudinal data were collected from 2130 Rush Memory and Aging Project participants. Participants underwent annual cognitive and psychological assessments and neuroimaging procedures every year. BDNF gene expression was measured in the dorsolateral prefrontal cortex, cytokines were measured in serum, and the final consensus clinical diagnosis was identified at the time of death. All linear mixed and multinomial logistic regression models controlled for age at baseline, education, sex, and APOE genotype. Participants were largely women (73 %), and Caucasian (93 %). The average education was 14.93 (SD = 3.34). The average age at baseline was 80.05 (SD = 7.57). Results showed that gray matter volume and depressive symptoms partially mediated the relationship between loneliness and cognitive decline. There was a significant interaction between loneliness and BDNF expression in relation to cognitive decline. Higher levels of BDNF expression was associated with slower decline in semantic memory and visuospatial ability. Finally, the current study also established that higher levels of loneliness was positively associated with the incidence of AD and other dementias. The present findings support the growing literature, which tends to show that the consequence of loneliness goes beyond the feeling of being isolated. Loneliness may induce physiological changes in our brains, leading to cognitive decline. Future research can explore a wide range of biological and psychological expressions of loneliness to clarify how loneliness relates to dementia.

Loneliness Predicts Progression of Frailty in Married and Widowed, but Not Unmarried Community Dwelling Older Adults

BACKGROUND

Loneliness is highly prevalent among older adults and is associated with frailty. Most studies consider loneliness in isolation without consideration for structural and functional measures of social relationships - and longitudinal studies are scarce.

OBJECTIVES

This study examined longitudinal associations between loneliness and frailty and analyzed how structural and functional social measures influence these associations.

DESIGN

Linear mixed effects models examined longitudinal associations between loneliness and frailty assessed with the frailty index (scale 0-100). Models were adjusted for baseline age, gender, education, depressive symptoms, global cognition, and structural (e.g., social network, marital status), and functional social measures (e.g., social, cognitive, and physical activity, and social support).

PARTICIPANTS

Loneliness and frailty data from 1,931 older adults without dementia at baseline from the Rush Memory and Aging Project were examined (mean age 79.6 ± 7.7 years, 74.9% female).

MEASUREMENTS

Baseline loneliness assessed by the de Jong Gierveld Loneliness Scale was the predictor of interest.

RESULTS

Frailty increased significantly over a mean follow-up period of 4.6 years. Effects of loneliness on frailty were modified by marital status. Loneliness predicted an additional accumulation of 0.37 and 0.34 deficits on the frailty index per year in married and widowed individuals respectively, compared to those who were not lonely (married: p=0.009, CI 0.09, 0.64; widowed: p=0.005, CI 0.1, 0.58). Loneliness did not predict frailty progression in unmarried individuals.

CONCLUSIONS

Loneliness predicts frailty progression, highlighting the importance of social determinants on physical health in aging.

Characterizing the mechanisms of social connection

Understanding how individuals form and maintain strong social networks has emerged as a significant public health priority as a result of the increased focus on the epidemic of loneliness and the myriad protective benefits conferred by social connection. In this review, we highlight the psychological and neural mechanisms that enable us to connect with others, which in turn help buffer against the consequences of stress and isolation. Central to this process is the experience of rewards derived from positive social interactions, which encourage the sharing of perspectives and preferences that unite individuals. Sharing affective states with others helps us to align our understanding of the world with another's, thereby continuing to reinforce bonds and strengthen relationships. These psychological processes depend on neural systems supporting reward and social cognitive function. Lastly, we also consider limitations associated with pursuing healthy social connections and outline potential avenues of future research.

Loneliness is related to smaller gray matter volumes in ACC and right VLPFC in people with major depression: a UK biobank study

The anterior cingulate cortex (ACC) and right ventrolateral prefrontal cortex (VLPFC) are thought to have important roles in loneliness (feeling of social isolation/exclusion) experience or regulation and in the pathophysiology of their disturbance in major depressive disorder (MDD). However, the structural abnormalities of these regions and the correlates with loneliness in MDD across the healthy population have not fully been clarified. The study analyzed the link between loneliness and gray matter volumes (GMVs) in the ACC and right VLPFC among 1,005 patients with MDD and 7,247 healthy controls (HCs) using UK Biobank data. Significant reductions in GMV in the right VLPFC were found in MDD males compared to HCs. MDD males also showed a higher association between loneliness and reduced GMVs in the right VLPFC and bilateral ACC than HCs. No such associations were found in MDD females. The findings suggest that loneliness may influence brain structures crucial for emotion experience and regulation, particularly in middle-older aged men with MDD. This highlights the potential adverse effects of loneliness on brain structure in MDD and suggests that social engagement could have a positive impact.

National Prevalence of Social Isolation and Loneliness in Adults with Chronic Obstructive Pulmonary Disease

Rationale: Social isolation and loneliness are gaining recognition for their role in health outcomes, yet they have not been defined in people with chronic obstructive pulmonary disease (COPD). Objective: To determine the national prevalence of and characteristics associated with social isolation and loneliness in people with COPD. Methods: This is a cross-sectional study of community-dwelling adults aged ⩾50 years in the nationally representative HRS (Health and Retirement Study) (2016-2018). Participants self-reported COPD and supplemental oxygen use and were categorized into three groups: 1) no COPD; 2) COPD; and 3) COPD on oxygen. Social isolation was defined using a nine-item scale indicating minimal household contacts, social network interaction, and community engagement. Loneliness was measured using the 3-Item UCLA Loneliness Scale. Multivariable logistic regression defined prevalence and associated characteristics for both. Results: Participants (n = 10,384) were on average 68 years old (standard deviation, ±10.5), 54% female, 10% Black, 11% self-reported COPD, and 2% self-reported supplemental oxygen. Overall, 12% were socially isolated, 12% lonely, and 3% both socially isolated and lonely. People with COPD had a higher adjusted prevalence of social isolation (no COPD: 11%; COPD: 16%; COPD on oxygen: 20%; P < 0.05) and loneliness (no COPD: 11%; COPD: 18%; COPD on oxygen: 22%; P < 0.001). In those with COPD, characteristics associated with social isolation (P < 0.05) included sex (men: 22%; women: 13%), non-Hispanic White ethnicity (White: 19%; Black: 7%), low net worth (<$6,000: 32%; $81,001-$239,000: 10%), depression (depression: 24%; no depression: 14%), having difficulty with one or more activities of daily living (one or more difficulty: 22%; no difficulty: 14%), and current cigarette use (current: 24%; never: 13%). Characteristics associated with loneliness (P < 0.05) included younger age (50-64 yr: 22%; 75-84 yr: 12%), being single (single: 32%; married: 12%), depression (depression: 36%; no depression: 13%), having difficulty with one or more activities of daily living (one or more difficulty: 29%; no difficulty: 15%), diabetes (diabetes: 26%; no diabetes: 17%), and heart disease (heart disease 23%; no heart disease: 17%). Conclusions: Nearly one in six adults with COPD experience social isolation, and one in five experience loneliness, with almost twice the prevalence among those on supplemental oxygen compared with the general population. Demographic and clinical characteristics identify those at highest risk to guide clinical and policy interventions.

Experiences of Loneliness Across the Lifespan: A Systematic Review and Thematic Synthesis of Qualitative Studies

PURPOSE

Loneliness is a fundamentally subjective experience that is common at various life stages. Studies have qualitatively explored loneliness, but a comprehensive overview is lacking. This research therefore provides a fine-grained review of studies on loneliness experiences across the lifespan.

METHODS

A systematic review and thematic synthesis were performed on studies that qualitatively investigated experiences of loneliness in people of any age from non-clinical populations. Sensitivity analysis assessed the impact of lower-quality studies and specific age groups on the findings.

RESULTS

Twenty-nine studies of 1,321 participants aged between 7 and 103 were included. Fifteen descriptive themes and three overarching analytical themes were developed: (1) Loneliness is both psychological and contextual, (2) Loneliness centres on feelings of meaningful connection and painful disconnection, and (3) Loneliness can exist in a general, pervasive sense or can relate to specific other people or relationship types. Some features were particularly pertinent to children, younger adults, and older adults, respectively.

CONCLUSIONS

Loneliness involves a primarily aversive psychological experience of perceived disconnection which is linked to physical, personal, and socio-political contexts and can be pervasive or relate to specific relationships or relationship types. An awareness of context, life stage, and personal experiences is essential to understand loneliness.

Neurogenetics and Epigenetics of Loneliness

Loneliness, an established risk factor for both, mental and physical morbidity, is a mounting public health concern. However, the neurobiological mechanisms underlying loneliness-related morbidity are not yet well defined. Here we examined the role of genes and associated DNA risk polymorphic variants that are implicated in loneliness via genetic and epigenetic mechanisms and may thus point to specific therapeutic targets. Searches were conducted on PubMed, Medline, and EMBASE databases using specific Medical Subject Headings terms such as loneliness and genes, neuro- and epigenetics, addiction, affective disorders, alcohol, anti-reward, anxiety, depression, dopamine, cancer, cardiovascular, cognitive, hypodopaminergia, medical, motivation, (neuro)psychopathology, social isolation, and reward deficiency. The narrative literature review yielded recursive collections of scientific and clinical evidence, which were subsequently condensed and summarized in the following key areas: (1) Genetic Antecedents: Exploration of multiple genes mediating reward, stress, immunity and other important vital functions; (2) Genes and Mental Health: Examination of genes linked to personality traits and mental illnesses providing insights into the intricate network of interaction converging on the experience of loneliness; (3) Epigenetic Effects: Inquiry into instances of loneliness and social isolation that are driven by epigenetic methylations associated with negative childhood experiences; and (4) Neural Correlates: Analysis of loneliness-related affective states and cognitions with a focus on hypodopaminergic reward deficiency arising in the context of early life stress, eg, maternal separation, underscoring the importance of parental support early in life. Identification of the individual contributions by various (epi)genetic factors presents opportunities for the creation of innovative preventive, diagnostic, and therapeutic approaches for individuals who cope with persistent feelings of loneliness. The clinical facets and therapeutic prospects associated with the current understanding of loneliness, are discussed emphasizing the relevance of genes and DNA risk polymorphic variants in the context of loneliness-related morbidity.

The positive and negative emotion functions related to loneliness: a systematic review of behavioural and neuroimaging studies

Loneliness is associated with high prevalences of major psychiatric illnesses such as major depression. However, the underlying emotional mechanisms of loneliness remained unclear. We hypothesized that loneliness originates from both decreases in positive emotional processing and increases in negative emotion processing. To test this, we conducted a systematic review of 29 previous studies (total participants n = 19 560, mean age = 37.16 years, female proportion = 59.7%), including 18 studies that included questionnaire measures of emotions only, and 11 studies that examined the brain correlates of emotions. The main findings were that loneliness was negatively correlated with general positive emotions and positively correlated with general negative emotions. Furthermore, limited evidence indicates loneliness exhibited negative and positive correlations with the brain positive (e.g. the striatum) and negative (e.g. insula) emotion systems, respectively, but the sign of correlation was not entirely consistent. Additionally, loneliness was associated with the structure and function of the brain emotion regulation systems, particularly the prefrontal cortex, but the direction of this relationship remained ambiguous. We concluded that the existing evidence supported a bivalence model of loneliness, but several critical gaps existed that could be addressed by future studies that include adolescent and middle-aged samples, use both questionnaire and task measures of emotions, distinguish between general emotion and social emotion as well as between positive and negative emotion regulation, and adopt a longitudinal design that allows us to ascertain the causal relationships between loneliness and emotion dysfunction. Our findings provide new insights into the underlying emotion mechanisms of loneliness that can inform interventions for lonely individuals.

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.

Evaluation of brain nerve function in ICU patients with Delirium by deep learning algorithm-based resting state MRI

The purpose of this study was to explore the value of resting-state magnetic resonance imaging (MRI) based on the brain extraction tool (BET) algorithm in evaluating the cranial nerve function of patients with delirium in intensive care unit (ICU). A total of 100 patients with delirium in hospital were studied, and 20 healthy volunteers were used as control. All the subjects were examined by MRI, and the images were analyzed by the BET algorithm, and the convolution neural network (CNN) algorithm was introduced for comparison. The application effects of the two algorithms were analyzed, and the differences of brain nerve function between delirium patients and normal people were explored. The results showed that the root mean square error, high frequency error norm, and structural similarity of the BET algorithm were 70.4%, 71.5%, and 0.92, respectively, which were significantly higher than those of the CNN algorithm (P < 0.05). Compared with normal people, the ReHo values of pontine, hippocampus (right), cerebellum (left), midbrain, and basal ganglia in delirium patients were significantly higher. ReHo values of frontal gyrus, middle frontal gyrus, left inferior frontal gyrus, parietal lobe, and temporal lobe and anisotropy scores (FA) of cerebellums (left), frontal lobe, temporal lobe (left), corpus callosum, and hippocampus (left) decreased significantly. The average diffusivity (MD) of medial frontal lobe, superior temporal gyrus (right), the first half of cingulate gyrus, bilateral insula, and caudate nucleus (left) increased significantly (P < 0.05). MRI based on the deep learning algorithm can effectively improve the image quality, which is valuable in evaluating the brain nerve function of delirium patients. Abnormal brain structure damage and abnormal function can be used to help diagnose delirium.