Loneliness in older adults is associated with diminished cortisol output

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.

The association between depression and the cortisol awakening response is moderated by loneliness in men from a non-clinical sample

Previous studies investigating cortisol levels in people with depression or depressive symptoms have provided mixed findings. It has been suggested that the difficulty to generalize findings across studies in this field might be related to interindividual variability in experiencing depressive symptoms in terms of clinical and social contexts. Therefore, in the present study we aimed to test the association of morning cortisol levels and depressive symptoms in a non-clinical sample of young men taking into consideration the level of perceived loneliness. We hypothesized that the level of loneliness might moderate the association between morning cortisol levels and depressive symptoms. A total of 102 participants (aged 29.9 ± 5.0 years) completed questionnaires measuring the levels of depressive and anxiety symptoms, perceived stress, and loneliness. Cortisol levels were determined in four morning samples of saliva. There were significant positive correlations of the cortisol awakening response (CAR) and the mean increase in cortisol levels during the measurement period (MnInc) with the levels of depressive symptoms and loneliness. Moreover, a significant association of the depressive symptoms by loneliness interaction with the CAR and the MnInc was found. Specifically, the correlation of depressive symptoms with the CAR and the MnInc appeared to be significant and negative at high levels of loneliness. No significant association between depressive symptoms and the CAR was observed in men with low levels of loneliness. There were no significant associations of depressive symptoms, loneliness and the depressive symptoms by loneliness interaction with cortisol levels at awakening. In conclusion, findings from the present study indicate the importance of social contexts in understanding the association between altered activity of the hypothalamic-pituitary-adrenal axis and depressive symptoms in men.

Social Loneliness in Older Adults with Mild Cognitive Impairment: Predictive Factors and Associated Clinical Characteristics

BACKGROUND

Loneliness and social isolation are considered public health problems among older individuals. In addition, both increase the risk of developing cognitive impairment and dementia. The Social Loneliness construct has been proposed to refer to these harmful social interaction-related factors.

OBJECTIVE

To define the risk factors of Social Loneliness in individuals with mild cognitive impairment (MCI) and to analyze cognitive, emotional, and functional differences according to the participant's degree of Social Loneliness.

METHODS

Through convenience sampling, 105 participants over 60 diagnosed with MCI were selected. The evaluation consisted of anamnesis and a comprehensive neuropsychological examination. The ESTE-II questionnaire was used to assess Social Loneliness and its three factors: perceived social support, social participation, and use of communication technologies. Personality was measured with the NEO-FFI questionnaire.

RESULTS

The predictors of the Social Loneliness factors were as follows; 1) perceived social support (R2 = 0.33): Neuroticism (β= 0.353), depression (β= 0.205), and perceived health (β= 0.133); 2) social participation (R2 = 0.24): Conscientiousness (β= -0.344) and Extraversion (β= -0.263); 3) use of communication technologies (R2 = 0.44): age (β= 0.409), type of cohabitation (β= 0.331), cognitive reserve (β= -0.303), and Conscientiousness (β= -0.247); all p < 0.05. The participants with a higher degree of Social Loneliness showed more depressive symptoms (R2 = 0.133), more memory complaints (R2 = 0.086), worse perceived health (R2 = 0.147), lower attentional performance/processing speed (R2 = 0.094), and more naming difficulties (R2 = 0.132); all p < 0.05.

CONCLUSIONS

This research represents an advance in detecting individuals with MCI and an increased risk of developing Social Loneliness, which influences the configuration of the clinical profile of MCI.

Associations between Social Isolation Index and changes in grip strength, gait speed, bone mineral density (BMD), and self-reported incident fractures among older adults: Results from the Canadian Longitudinal Study on Aging (CLSA)

BACKGROUND

The aim is to investigate whether social isolation and loneliness are associated with changes in grip strength, gait speed, BMD, and fractures.

METHODS

Canadian Longitudinal Study on Aging (CLSA) Comprehensive Cohort participants aged 65 years and older at baseline (2012-2015) who completed the three-year follow-up interview (2015-2018) were included in this analysis (n = 11,344). Social isolation and loneliness were measured using the CLSA social isolation index (CLSA-SII, range 0-10). We calculated absolute and percent change in grip strength (kg) and gait speed (m/s) and annualized absolute (g/cm2) and percent change in femoral neck and total hip BMD during the three-year follow-up. Self-reported incident fractures of all skeletal sites in the previous 12 months were measured at three-year follow-up. Multivariable analyses were conducted. Odd ratio (OR) and 95% confidence interval (CI) are reported.

RESULTS

The mean age (standard deviation [SD]) was 72.9 (5.6) years and 49.9% were female. The mean (SD) of CLSA-SII at baseline was 3.5 (1.4). Mean absolute and percentage change (SD) in grip strength (kg) and gait speed (m/s) were -1.33 (4.60), -3.02% (16.65), and -0.05 (0.17), -3.06% (19.28) during the three-year follow-up, respectively. Mean annualized absolute (g/cm2) and percentage change (SD) in femoral neck and total hip BMD were -0.004 (0.010), -0.47% (1.43) and -0.005 (0.009), -0.57% (1.09), respectively. 345 (3.1%) participants had incident fractures. As CLSA-SII increased (per one unit change), participants had 1.13 (adjusted OR 1.13, 95% CI 1.01-1.27) times greater odds for incident fractures. The interaction term between the CLSA-SII and centre for epidemiology studies depression 9 scale (CES-D 9) for self-reported incident fractures was shown (interaction OR 1.02, 95% CI 1.00-1.04).

CONCLUSIONS

Socially isolated and lonely older adults were more likely to have had incident fractures, but social isolation was not associated with the three-year changes in grip strength, gait speed, or BMD.

How does loneliness "get under the skin" to become biologically embedded?

Loneliness is linked to declining physical health across cardiovascular, inflammatory, metabolic, and cognitive domains. As a result, loneliness is increasingly being recognized as a public health threat, though the mechanisms that have been studied do not yet explain all loneliness-related health risk. Potential mechanisms include loneliness having 1.) direct, causal impacts on health, possibly maintained by epigenetic modification, 2.) indirect effects mediated through health-limiting behaviors, and 3.) artifactual associations perhaps related to genetic overlap and reverse causation. In this scoping review, we examine the evidence surrounding each of these pathways, with a particular emphasis on emerging research on epigenetic effects, in order to evaluate how loneliness becomes biologically embedded. We conclude that there are significant gaps in our knowledge of how psychosocial stress may lead to physiological changes, so more work is needed to understand if, how, and when loneliness has a direct influence on health. Hypothalamic-pituitary adrenocortical axis disruptions that lead to changes in gene expression through methylation and the activity of transcription factor proteins are one promising area of research but are confounded by a number of unmeasured factors. Therefore, wok is needed using causally informative designs, such as twin and family studies and intensively longitudinal diary studies.

Sex-related differences in the associations between diurnal cortisol pattern and social and emotional loneliness in older adults

Introduction

Loneliness is a distressful feeling that can affect mental and physical health, particularly among older adults. Cortisol, the primary hormone of the Hypothalamic-Pituitary-Adrenal axis (HPA-axis), may act as a biological transducer through which loneliness affects health. While most previous studies have evaluated the association between loneliness, as a unidimensional construct, and diurnal cortisol pattern, no research has examined this relationship discriminating between social and emotional loneliness in older adults. As sex differences in the negative mental health outcomes of loneliness have been reported, we also investigated whether diurnal cortisol indices and loneliness associations occur in a sex-specific manner.

Methods

We analyzed the diurnal cortisol- pattern in 142 community-dwelling, non-depressed, Caucasian older adults (55,6% female) aged 60-90. Social and emotional (family and romantic) loneliness scores were assessed using the Spanish version of the Social and Emotional Loneliness Scale for Adults (SELSA). Five salivary cortisol samples were used to capture key features of the diurnal cortisol pattern, including: awakening and bedtime cortisol levels, awakening response (CAR), post-awakening cortisol output (post-awakening cortisol [i.e., the area under the curve with reference to the ground: AUCG]), total diurnal cortisol release (AUCG), and diurnal cortisol slope (DCS).

Results

After controlling for sociodemographic variables, the hierarchical linear multiple regression analyses revealed that in male older adults, higher scores on social and family loneliness were associated with elevated awakening cortisol levels, total diurnal cortisol output, and a steeper diurnal cortisol slope (DCS). However, these associations were not observed in female older adults. In addition, feelings of romantic loneliness were positively associated with bedtime cortisol levels and AUCG in older males. Multilevel growth curve modeling showed that experiencing more social and emotional loneliness predicted higher diurnal cortisol output throughout the day in older male adults.

Discussion

The presence of sex differences in the relationship between cortisol indices and loneliness among older adults holds particular significance for diagnostic and screening procedures. Combining loneliness scales as screening tools with diurnal cortisol measures has the potential to be an effective and cost-efficient approach in identifying higher-risk individuals at early stages.

The diurnal course of salivary cortisol and alpha-amylase on workdays and leisure days in teachers and the role of social isolation and neuroticism

Teachers are among the occupational groups with the highest sick leave rates due to workplace stress and burnout symptoms. A substantial body of research has suggested social isolation and neuroticism to be related to physiological stress activity. However, the relationship between such characteristics and stress experiences has rarely been studied in conjunction with physiological stress indicators in the teachers' natural settings. Thus, the present study examines salivary cortisol and α-amylase as physiological stress indicators on teachers' work and leisure days and their relationship with social isolation. Furthermore, we test whether neuroticism moderates the relationship between social isolation and salivary biomarkers. Forty-two teachers completed questionnaires assessing social isolation (Trier Inventory for the Assessment of Chronic Stress) and neuroticism (Big-Five Inventory). Participants collected eight saliva samples on three days, two workdays, and one leisure day to measure the concentration of cortisol and α-amylase as biomarkers of the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), respectively. Results showed a significantly higher Cortisol Awakening Response (CAR) and diurnal cortisol slope (DCS) on workdays than on the leisure day but no significant differences regarding measures of α-amylase. We found a significant positive relationship between social isolation and the CAR on the leisure day but no association with the α-amylase measures. Furthermore, after controlling for confounders, social isolation was unrelated to neuroticism, and the latter did not moderate between social isolation and the CAR. Our findings suggest an association between social isolation and the HPA axis, i.e., the CAR, but do not support an association with the ANS, which would be indicated by the α-amylase assessments. Finally, our findings could not support an association of neuroticism with the HPA axis and ANS.

Physical Activity and Cortisol Regulation: A Meta-Analysis

Physical activity participation is associated with effective stress coping, indicated by decreases in both physiological stress reactivity and perceived stress. Quantifying the effect of physical activity on the diurnal regulation of one key physiological stress indicator, the stress hormone, cortisol, across studies may demonstrate the extent to which physical activity participation is associated with diurnal HPA axis regulation. We meta-analyzed studies examining relations between physical activity participation and indices of HPA axis regulation: the diurnal cortisol slope and the cortisol awakening response. We also examined moderators of the relation. The analysis revealed a small, non-zero negative averaged correlation between physical activity and the diurnal cortisol slope (r = -0.043, 95% CI [-0.080, -0.004]). Examination of sample sociodemographic differences, study design characteristics, cortisol measurement methods, and physical activity variables as moderators revealed few effects on the relation between physical activity and diurnal cortisol slope. We did not observe lower levels of variability in the mean cortisol awakening response at higher levels of physical activity participation, and moderator analyses showed little evidence of reductions in heterogeneity for this effect. We found some evidence of systematic publication bias. Findings suggest higher physical activity is associated with a steeper diurnal cortisol slope. However, the cortisol awakening response did not differ by physical activity level. Future studies testing the physical activity and cortisol regulation association should use standardized physical activity measures, follow guidelines for better quality cortisol sampling collection and analysis, and test relations in large-scale empirical studies to confirm the direction and causality of the effect.

The Association Between Loneliness and Psychiatric Symptomatology in Older Psychiatric Outpatients

PURPOSE

Loneliness in adults increases with age. Although loneliness has been found to be associated with psychiatric disorders and dementia, no information is available on prevalence of loneliness in older psychiatric patients. The aims of this study were to examine prevalence of loneliness in older psychiatric outpatients, including gender differences and associations with psychiatric disorders and social isolation.

METHODS

Cross-sectional study in an outpatient clinic for geriatric psychiatry between September 2013 and February 2018. Interviews were done in 181 patients.

RESULTS

80% of participants were lonely. Loneliness was associated with having contacts in less social network domains, in women but not in men. There were no associations with DSM-IV-TR-classifications. However, loneliness was associated with higher scores on questionnaires for depression and cognitive function. Intensity of treatment did not differ significantly between lonely and non-lonely participants.

CONCLUSION

Loneliness is highly prevalent in older psychiatric outpatients, with men and women equally affected. Loneliness should be assessed in all older psychiatric patients, especially when they show high scores on symptom checklists or have a restricted social network.

Loneliness and Health Indicators in Middle-Aged and Older Females and Males

Loneliness is a complex and uncomfortable feeling that results from the perception of a lack of desired personal and social ties. Loneliness is accentuated with aging. It has been related to a wide range of objective and subjective health indicators and is a risk factor for morbidity and mortality. One of the proposed underlying mechanisms through which loneliness affects health is the dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis. However, the relationship between loneliness and cortisol, the main product of the HPA axis, is unclear and requires more research. The aims of this cross-sectional study were to investigate the relationships between loneliness, subjective health, and cortisol indexes, taking the sex into account, and investigate whether the HPA axis mediates the relationship between loneliness and subjective health. For this purpose, 79 participants (between 55 and 75 years old) completed several scales on loneliness, depression, perceived stress, psychological and physical health, and social relationships. Various salivary cortisol measurements were obtained on two consecutive days. The initial results showed that loneliness was related to psychological and physical health in the mixed-sex sample. However, when covariates were introduced, loneliness was only associated with psychological health in males. In addition, the cortisol indexes employed were not related to loneliness and did not mediate the relationship between loneliness and subjective health. Hence, we did not find a relevant role of the HPA axis in the association between loneliness and subjective health. More severe perceptions of loneliness would probably be necessary to detect this role. Overall, these results also show that the expected negative outcomes of loneliness associated with aging can be countered by an active life that can compensate for the natural losses experienced with age or at least delay these negative outcomes. Finally, some sex differences were found, in line with other studies, which warrants further examination of social variables and dimensions related to gender in future research.

Loneliness, social network size, and mortality in older adults and the role of cortisol

BACKGROUND

Loneliness and social isolation have both been found to be associated with increased mortality in previous studies. One potential underlying mechanism is via the hypothalamic-pituitary-adrenal axis.

OBJECTIVE

This study aimed to examine the association between social network size and cortisol, to analyze the associations between both loneliness and social network size and mortality, and to examine to what extent the association between network size and/or loneliness and mortality is mediated by cortisol.

DESIGN

The study group consisted of 443 depressed and non-depressed participants of the Netherlands Study of Depression in the Elderly (NESDO). Cross-sectional analysis of the association between social network size and cortisol measures was followed by a survival analysis of the associations between both social network size and loneliness and mortality.

RESULTS

There were no significant associations between social network size and cortisol measures. Loneliness and small social network size were not associated with mortality. Age and partner status were more important predictors of mortality.

CONCLUSION

As people grow older the variety of factors that influence mortality risk increases, diminishing the effect of a single factor. Prevention of early morbidity and mortality in older adults should be tailored to specific needs and risks, instead of aiming at one specific factor.

An examination of reciprocal effects between cardiovascular morbidity, depressive symptoms and loneliness over time in a longitudinal cohort of Dutch older adults

BACKGROUND

Unidirectional studies suggest that the effects between cardiovascular disease, depressive symptoms and loneliness are reciprocal, but this has not been tested empirically. The aim was to study how cardiovascular morbidity, depressive symptoms and loneliness influence each other longitudinally.

METHODS

Data from 2979 older adults from the Longitudinal Aging Study Amsterdam were analysed. Depressive symptoms (≥16 points on the Center for Epidemiologic Studies Depression Scale), loneliness (≥3 points on the De Jong Gierveld Loneliness Scale) and cardiovascular morbidity were measured five times during 13-year follow-up. With structural equation modelling, a full cross-lagged panel model was compared to nine nested models reflecting different sets of temporal effects.

RESULTS

The best-fitting cross-lagged panel model showed reciprocal risk increasing effects between depressive symptoms and loneliness and a risk increasing effect of cardiovascular morbidity on depressive symptoms.

LIMITATIONS

A cross-lagged panel model has technical limitations, such as that the chosen time lag may not be appropriate for each effect. In addition, differential loss to follow-up and collider bias may have led to an underestimation of the effects.

CONCLUSIONS

Reciprocal effects tend to occur only between depressive symptoms and loneliness. Their interplay with cardiovascular morbidity seems more complex and mostly indirect, highlighting the potential of interventions to reduce depressive symptoms, loneliness and cardiovascular morbidity in concert to improve health at old age.

Married but lonely. Impact of poor marital quality on diurnal cortisol patterns in older people: findings from the cross-sectional KORA-Age study

Despite well-established evidence on marriage as a psychosocial support for adults, there are studies that indicate loneliness may affect even married adults. Loneliness provokes a dysregulation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Thus, the study aims to examine the sex-specific association of loneliness and cortisol levels in the married older population. A cross-sectional analysis was conducted among 500 married participants (316 male and 184 female) aged 65-90 years (mean age = 73.8 ± 6.4 years) of the population-based KORA (Cooperative Health Research in the Region of Augsburg) - Age study. Linear regression analyses were employed to examine the association between cortisol measurements (salivary cortisol upon waking (M1), 30 min after awakening (M2), late night (LNSC), cortisol awakening response (CAR), diurnal cortisol slope (DCS)) and loneliness (assessed by UCLA Loneliness Scale) in married participants with adjustments for potential confounders. In total sample population, lonely married participants displayed a significantly flatter DCS after M2 peak than their not lonely counterparts. In sex-specific analyses, lonely married men showed flatter DCS and reduced CAR than non-lonely counterparts. The association between loneliness and DCS was robust even after adjustment for lifestyle and psychosocial factors. In married women, no significant associations between loneliness and cortisol levels were observed. These findings suggest a differential impact of loneliness on HPA axis dynamics in lonely married men. Our findings highlight the importance to address loneliness even in married people.

Social Isolation and Loneliness in Older Adults: Review and Commentary of a National Academies Report

The authors of this review both served on the National Academy of Science, Engineering, and Medicine Committee that produced the report, "Social Isolation and Loneliness in Older Adults: Opportunities for the Health Care System." In 2018, the AARP Foundation commissioned the National Academies to establish a committee to research and develop a report on social isolation and loneliness in persons 50 years of age and older. Emphasis was placed upon the role of the healthcare system in addressing this fundamental public health problem. The committee released the report in February 2020 as the Corona Virus Disease 2019 pandemic was beginning to spread to North America. In this review, the authors share central findings and conclusions from the report as well as how these findings may be relevant to the care and well-being of older adults during this historic pandemic. The health protective benefits of social distancing must be balanced by the essential need for sustaining social relationships.

Neuroendocrine mechanisms of grief and bereavement: A systematic review and implications for future interventions

Bereavement is associated with many negative behavioural, psychological and physiological consequences and leads to an increased risk of mortality and morbidity. However, studies specifically examining neuroendocrine mechanisms of grief and bereavement have yet to be reviewed. This systematic review is a synthesis of the latest evidence in this field and aims to draw conclusions about the implications of neurobiological findings on the development of new interventions. PRISMA guidelines for systematic reviews were used to search for articles assessing neuroendocrine correlates of grief. Findings were qualitatively summarised. The National Heart, Lung, and Blood Institute Study Assessment Tool was used to assess the quality of the included studies. Out of 460 papers, 20 met the inclusion criteria. However, most were of fair quality only. As a neuroendocrine marker, the majority of the studies reported cortisol as the outcome measure and found elevated mean cortisol levels, flattened diurnal cortisol slopes and higher morning cortisol in bereaved subjects. Cortisol alterations were moderated by individual differences such as emotional reaction to grief, depressive symptoms, grief severity, closeness to the deceased and age or gender. Research on neuroendocrine mechanisms of grief is still in its early stages regarding grief measures and the use and timing of neuroendocrine assessments. Most of the studies focus on cortisol as outcome, and only limited data exist on other biomarkers such as oxytocin. Future research might consider assessing a broader range of neuroendocrine markers and use longitudinal designs with a focus on the psychobiological reactions to loss. Based on this, individually tailored psychosocial interventions, possibly in the palliative care context, might be developed to prevent prolonged grief disorder.

Stability of clinically relevant depression symptoms in old-age across 11 cohorts: a multi-state study

AIMS

To study the temporal dynamics of depression symptom episodes in old-age and the related influence of risk factors.

METHODS

Data from 41 362 old adults (54.61% women; mean age = 75.30, SD = 6.20) from the Ageing Trajectories of Health - Longitudinal Opportunities and Synergies (ATHLOS) project were used. Depressive symptoms were followed over an 18-year period. A multi-state model, comprising three statuses (no depression, new clinically relevant episode of symptoms and episode persistence), was fitted. Multinomial regression was used to study the role of risk factors in status transition.

RESULTS

Almost 85% of participants showed no depression, but prevalence became lower over time (B = -0.25, P < 0.001). New episode point prevalence was over 5.30% with a significant probability of moving to persistence status (transition probability = 0.27). Episode persistence became evident in 9.86% of episode status transitions, with increasing rate over time (B = 0.54, P < 0.01). Loneliness was proven to be the strongest predictor of episode emergence (OR = 17.76) and persistence (OR = 5.93).

CONCLUSIONS

The course of depression tends to become chronic and unremitting in old-age. This study may help to plan interventions to tackle symptom escalation and risk factor influence.

Daily hassles, loneliness, and diurnal salivary cortisol in emerging adults

This study used an intensive protocol to examine the effects of daily hassles and loneliness on diurnal salivary cortisol levels. Fifty Chinese undergraduates (28 females) provided six saliva samples each day for two consecutive days (at 0, 0.5, 3, 6, and 12 h after waking and at bedtime) and completed a questionnaire that included scales to measure daily hassles experienced over the previous month, trait loneliness, and depression. Cortisol data were aggregated over two days and used in subsequent analyses, focusing on the cortisol awakening response, diurnal slope, and overall cortisol output operationalized as the area under the curve with reference to the ground (AUC_G). Multiple regression analysis showed that an increase in loneliness had a significant association with an increase in the AUC_G and with a steeper diurnal slope. Loneliness also showed a significant interaction with daily hassles in that the positive association between daily hassles and AUC_G was accentuated in the participants who reported a greater degree of loneliness. Our findings demonstrate for the first time the importance of trait loneliness in modulating the association between daily hassles and diurnal cortisol levels, which has significant clinical implications. Interventions to reduce loneliness should help college students to better cope with daily stressors. Increased attention should also be paid to the health implications of an elevated cortisol level in this relatively young and healthy population.

The relationship between loneliness and cognition in healthy older men and women: The role of cortisol

Loneliness has been associated with an increased risk of cognitive decline and dementia in older people, as well as a dysregulation of Hypothalamic-Pituitary-Adrenal (HPA) axis functioning. In addition, it has been suggested that women are more vulnerable to the negative effects of loneliness on health. Our aim was to analyze the effect of HPA-axis functioning as a mediator in the relationship between loneliness and cognitive function, and interactions depending on sex, in healthy older people. To do so, 86 healthy older people (52.3% female) from 60 to 80 years old (M = 67.44, SD = 4.37) completed the revised UCLA loneliness scale. A neuropsychological battery was administered to assess global cognition, processing speed, attention and executive function, working memory, and verbal memory immediate and delayed recall. Saliva samples were provided on two consecutive weekdays to obtain awakening and bedtime cortisol levels, the diurnal cortisol slope (DCS), and the area under the curve with respect to the ground (AUCg). Our results showed that loneliness was not directly associated with cognitive performance. Furthermore, loneliness was related to higher bedtime cortisol levels, but not to awakening cortisol, the DCS, or the AUCg. In addition, loneliness was associated with worse performance on attention and processing speed, executive function, and verbal memory immediate recall, via bedtime cortisol levels. Therefore, we suggest that HPA-axis functioning is one of the biological mechanisms that mediate the relationship between loneliness and poorer cognitive function. No sex differences were observed in these associations.

Loneliness in adults: Evidence-based research and interventions for NPs

Loneliness is a complex psychophysiologic concept, a health risk factor, and a worrisome trend across the globe. This article reviews the latest research on the negative health effects associated with loneliness. Evidence-based NP interventions aimed at improving patients' perceived social connections are also explored.

Loneliness and Diurnal Salivary Cortisol in Emerging Adults

This study aimed to examine the relationship between trait loneliness and diurnal rhythms of salivary cortisol. Fifty-One Chinese undergraduates provided six saliva samples on a weekday at immediately, 0.5, 3, 6, and 12 h after waking, and at bedtime. Saliva collection times were monitored using electronic devices (MEMS TrackCaps). Participants were also administered a questionnaire consisting of scales measuring, trait loneliness, depression, and demographics. Relationships between loneliness and the cortisol awakening response (CAR), diurnal slope (DS), and area under the curve with respect to ground (AUC_G) were examined using multiple regression analyses. Results showed that a higher loneliness score was associated with an attenuated CAR, a large AUC_G, and a steeper DS, with the effects of compliance, waking time, and depression being controlled. As a blunted CAR and a higher diurnal cortisol level have been shown to be associated with poorer health in prior studies, increased attention to the mechanisms translating loneliness into disease endpoints via elevated cortisol is warranted.

Novel approaches to alcohol rehabilitation: Modification of stress-responsive brain regions through environmental enrichment

Relapse remains the most prominent hurdle to successful rehabilitation from alcoholism. The neural mechanisms underlying relapse are complex, but our understanding of the brain regions involved, the anatomical circuitry and the modulation of specific nuclei in the context of stress and cue-induced relapse have improved significantly in recent years. In particular, stress is now recognised as a significant trigger for relapse, adding to the well-established impact of chronic stress to escalate alcohol consumption. It is therefore unsurprising that the stress-responsive regions of the brain have also been implicated in alcohol relapse, such as the nucleus accumbens, amygdala and the hypothalamus. Environmental enrichment is a robust experimental paradigm which provides a non-pharmacological tool to alter stress response and, separately, alcohol-seeking behaviour and symptoms of withdrawal. In this review, we examine and consolidate the preclinical evidence that alcohol seeking behaviour and stress-induced relapse are modulated by environmental enrichment, and these are primarily mediated by modification of neural activity within the key nodes of the addiction circuitry. Finally, we discuss the limited clinical evidence that stress-reducing approaches such as mindfulness could potentially serve as adjunctive therapy in the treatment of alcoholism. This article is part of the Special Issue entitled "Neurobiology of Environmental Enrichment".

Loneliness and acute stress reactivity: A systematic review of psychophysiological studies

Physiological reactivity to acute stress has been proposed as a potential biological mechanism by which loneliness may lead to negative health outcomes such as cardiovascular disease. This review was conducted to investigate the association between loneliness and physiological responses to acute stress. A series of electronic databases were systematically searched (PsycARTICLES, PsycINFO, Medline, CINAHL Plus, EBSCOhost, PubMed, SCOPUS, Web of Science, Science Direct) for relevant studies, published up to October 2016. Eleven studies were included in the review. Overall, the majority of studies reported positive associations between loneliness and acute stress responses, such that higher levels of loneliness were predictive of exaggerated physiological reactions. However, in a few studies, loneliness was also linked with decreased stress responses for particular physiological outcomes, indicating the possible existence of blunted relationships. There was no clear pattern suggesting any sex- or stressor-based differences in these associations. The available evidence supports a link between loneliness and atypical physiological reactivity to acute stress. A key finding of this review was that greater levels of loneliness are associated with exaggerated blood pressure and inflammatory reactivity to acute stress. However, there was some indication that loneliness may also be related to blunted cardiac, cortisol, and immune responses. Overall, this suggests that stress reactivity could be one of the biological mechanisms through which loneliness impacts upon health.