Conditions Of Social Isolation Research Articles

Long-term voluntary exercise prevents post-weaning social isolation-induced cognitive impairment in rats

This study aimed to determine the effect of exercise on locomotion, anxiety-related behavior, learning, and memory in socially isolated post-weaning rats, as well as the correlation between exercise and the concentration of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the hippocampus. Rats were randomly assigned to three groups: the control group; the social isolation group; the social isolation plus exercise (SIE) group. Social isolation conditions, with or without exercise were maintained for 90d, and then multiple behavioral tests, including the open-field test, elevated plus maze test, and Morris water maze (MWM) test were administered. Following behavioral assessment, hippocampal tissue samples were obtained for measurement of BDNF and NGF. There wasn’t a significant difference in locomotor activity between the groups (P>0.05). Anxiety scores were higher in the socially isolated group (P<0.05) than in the SIE group (P<0.05). According to the probe trial session of the MWM test results, exercise training improved platform crossings’ number in the socially isolated rats (P<0.05). Exercise training ameliorated social isolation-induced reduction in hippocampal BDNF and NGF content (P<0.05). These findings suggest that exercise training improves cognitive functions via increasing hippocampal BDNF and NGF concentrations in socially isolated post-weaning rats.

Association between maternal social deprivation and prenatal care utilization: the PreCARE cohort study

BackgroundMaternal social deprivation is associated with an increased risk of adverse maternal and perinatal outcomes. Inadequate prenatal care utilization (PCU) is likely to be an important intermediate factor. The health care system in France provides essential health services to all pregnant women irrespective of their socioeconomic status. Our aim was to assess the association between maternal social deprivation and PCU.MethodsThe analysis was performed in the database of the multicenter prospective PreCARE cohort study. The population source consisted in all parturient women registered for delivery in 4 university hospital maternity units, Paris, France, from October 2010 to November 2011 (N = 10,419). This analysis selected women with singleton pregnancies that ended after 22 weeks of gestation (N = 9770). The associations between maternal deprivation (four variables first considered separately and then combined as a social deprivation index: social isolation, poor or insecure housing conditions, no work-related household income, and absence of standard health insurance) and inadequate PCU were tested through multivariate logistic regressions also adjusted for immigration characteristics and education level.ResultsAttendance at prenatal care was poor for 23.3% of the study population. Crude relative risks and confidence intervals for inadequate PCU were 1.6 [1.5–1.8], 2.3 [2.1–2.6], and 3.1 [2.8–3.4], for women with a deprivation index of 1, 2, and 3, respectively, compared to women with deprivation index of 0. Each of the four deprivation variables was significantly associated with an increased risk of inadequate PCU. Because of the interaction observed between inadequate PCU and mother’s country of birth, we stratified for the latter before the multivariate analysis. After adjustment for the potential confounders, this social gradient remained for women born in France and North Africa. The prevalence of inadequate PCU among women born in sub-Saharan Africa was 34.7%; the social gradient in this group was attenuated and no longer significant. Other factors independently associated with inadequate PCU were maternal age, recent immigration, and unplanned or unwanted pregnancy.ConclusionSocial deprivation is independently associated with an increased risk of inadequate PCU. Recognition of risk factors is an important step in identifying barriers to PCU and developing measures to overcome them.

Effect of 72 h of Sleep Deprivation on the Iowa Gambling Task.

Sleep deprivation has detrimental effects on cognitive processes, including decision making. The present study investigated how 72 h of sleep deprivation influenced individual neural performance in the Iowa gambling task using event-related potential technology. Eleven healthy male adults who participated in our study were randomized to be either in group with 72 h of social isolation condition or 72 h of sleep deprivation condition. Results showed that, in the feedback stage, the N250-400 amplitude was smaller in post-test than in pre-test for the sleep deprivation condition, especially in the frontal cortex. No significant difference between the pre-test and post-test condition was found in the social isolation condition. These results suggested that 72 h of sleep deprivation affected an individual's response to feedback stimuli, causing the individual to evaluate the stimuli slowly.

Astressin, an antagonist of CRF receptors, reduces anxiety and fobial states in rats reared in social isolation conditions

The influence of intranasal administration of astressin, a nonselective antagonist of CRF receptors, on delayed effects of chronic social isolation in the five first weeks after mother leaving on explorative and emotional behavior in rats was studied. Social exposures were applied from 21st to 93rd days of life. The rats reared in social isolation demonstrated higher level of motor activity compared with control in open field test. The assessment of both anxiety and fobial state and behavior in elevated plus maze revealed higher levels in anxiety and fear in isolated rats. Intranasal administration of astressin (1 µg/1µl, 20 µl, 10 µl in every nostrils) reduced significantly anxiety and fear levels in isolated rats. Therefore, both anxiolytic and antifobial effects of astressin, a nonselective antagonist of CRF receptors, were demonstrated in rats exposured to social isolation stress. The results support the idea taking into account the corticoliberin mechanisms in formation of social isolation syndrome and possibilities of using CRF antagonists to control the central stress mechanisms and dependence in ontogeny.

I can time with a little help from my friends: effect of social enrichment on timing processes in Pigeons (Columba livia).

There is evidence that impulsive decision-making is associated with errors in timing. However, there has been little attempt to identify the putative mechanism responsible for impulsive animals' timing errors. One means of manipulating impulsivity in non-human animals is providing different levels of access to conspecifics. These preclinical models have revealed that social isolation increases impulsive responding across a wide range of tasks. The goal of the present study was to determine whether social isolation modulates time perception in pigeons by inducing more variability or a bias to underestimate the passage of time in temporal judgments. A temporal bisection task was used to characterize time perception. One group of pigeons performed the bisection following social enrichment, and the remaining half of the pigeons were tested following social isolation. Results revealed pigeons in the social isolation condition categorized a temporal stimulus sample as "long" at shorter durations than pigeons in the social enrichment condition. These data highlight the mechanism(s) thought to underlie timing-based interventions aimed at reducing impulsivity in humans. Future work should consider whether impulsivity is produced by misperceptions of time or a reduced threshold for a response.

Intrinsic survival advantage of social insect queens depends on reproductive activation.

The central trade-off between reproduction and longevity dominates most species' life history. However, no mortality cost of reproduction is apparent in eusocial species, particularly social insects in the order Hymenoptera: one or a few individuals (typically referred to as queens) in a group specialize on reproduction and are generally longer lived than all other group members (typically referred to as workers), despite having the same genome. However, it is unclear whether this survival advantage is due to social facilitation by the group or an intrinsic, individual property. Furthermore, it is unknown whether the correlation between reproduction and longevity is due to a direct mechanistic link or an indirect consequence of the social role of the reproductives. To begin addressing these questions, we performed a comparison of queen and worker longevity in the ant Cardiocondyla obscurior under social isolation conditions. Survival of single queens and workers was compared under laboratory conditions, monitoring and controlling for brood production. Our results indicate that there is no intrinsic survival advantage of queens relative to workers unless individuals are becoming reproductively active. This interactive effect of caste and reproduction on life expectancy outside of the normal social context suggests that the positive correlation between reproduction and longevity in social insect queens is due to a direct link that can activate intrinsic survival mechanisms to ensure queen longevity.

A study on the social behavior and social isolation of the elderly Korea

This study aimed at presenting what factors are to predict the social isolation of the elderly as an element to prevent the problem of why various matters related to old people are inevitably taking place by carefully examining the meaning of social isolation and the conditions of social isolation that the South Korean senior citizens go through after working on previous studies. This section discusses the results obtained through document analysis. First, the aspects of the elderly’s social isolation arising from the changes of the South Korean society are changes of family relationship, the social structure, the economic structure and the culture. Second, the social isolation and social activity of the elderly are problems (suicide, criminals, dementia, depression and medical costs) of the elderly, change trend of the elderly issues related to social isolation and prediction factors that personal and regional. Lastly, as a role and challenges of the field of rehabilitation exercise aimed at resolving social isolation should be vitalized such as the development and provision of various relationship-building programs.

Behavioral and endocrine evaluation of the stressfulness of single-pen housing compared to group-housing and social isolation conditions

Regulation of neuroendocrine responses is often studied in animals housed indoors in individual contiguous pens. In sheep, these housing conditions are used to control the environment, facilitate biological sampling and limit social stress. However, this type of housing also prevents exploratory behaviors and could induce stereotypies, non-compliant with welfare and possibly associated with a state of stress. In this context, we investigated the impact of housing in a single-pen, with other familiar conspecifics, on emotional state by evaluating behavioral, hormonal and neuronal measures in adult ewes. We hypothesized that emotional state would be more negative in animals housed in a single-pen for one week (Pen) than in freely moving animals (Free) but less negative than in socially isolated subjects (Isol). We tested our hypothesis in ovariectomized ewes to avoid the interaction with sexual steroid variations. Our behavioral, endocrine and neuronal (Fos activation of the corticotropin-releasing hormone neurons in the paraventricular nucleus of the hypothalamus) measures confirmed that withdrawing familiar conspecifics was sufficient to induce strong stress responses in Isol ewes, but there was no indication that Pen ewes were stressed. However, the latter showed less mastication activity than Free ewes, probably due to limited accessibility to straw. The highest plasma prolactin levels were observed in Isol and Free animals, which might result from stress and physical activity, respectively. In Free ewes, plasma dopamine was low, consistent with its inhibitory control of prolactin. However, Isol animals had both high levels of prolactin and dopamine, suggesting a dysregulated balance in socially stressed ewes. As in other species, we suggest that the regulation of prolactin by dopamine varies with stress and/or social context. Overall, this study shows that the impact of housing conditions on different neuroendocrine systems should be considered more in the future.

Blockade of NMDA receptors reverses the depressant, but not anxiogenic effect of adolescence social isolation in mice

Early life social isolation stress (SIS), a well-known chronic stress paradigm, is contributed to a number of pathophysiological and neurochemical changes including depression and anxiety. The underlying mechanisms for these disorders in socially isolated animals have not been fully cleared. Previous studies have shown that N-Methyl-d-aspartate (NMDA) receptor function is changed by social isolation condition. It is now well recognized that NMDA receptor blockade can exhibit antidepressant and anxiolytic actions. In our study, postnatal day 21–25 mice were randomly housed for 4 weeks under either social condition (SC) or isolated condition (IC). Then, animals were subjected to different behavioral experiments to investigate whether blockade of NMDA receptor resulted in behavioral alterations in animals. Social isolation stress induced depressive and anxiety-like behaviors in IC animals in comparison with SC mice. Also, we applied subeffective doses of antagonists including ketamine (1mg/kg), MK-801 (0.05mg/kg), and magnesium sulfate (10mg/kg) to both SC and IC mice prior to behavioral experiments. Administration of a single dose of all mentioned drugs did not affect the SC mice but modulated the depressant effects of SIS on IC mice. Administration of NMDA receptor antagonists decreased the immobility time in the forced swimming test as well as an increase in grooming behavior in splash test. However, anxiety-like behaviors in IC animals remained unchanged in hole-board test and open field test after blockade of NMDA receptors. Taken together, our results showed the possible involvement of the NMDA receptors in the depressive, but not anxiety-like behaviors induced by SIS.

Malnutrition and social isolation among elderly residents of city public housing

The aim of this study was to examine relations between malnutrition and social isolation among elderly residents of a city public housing facility. The present participants were 442 residents aged 65 and older of a public housing facility in Nagoya city. An anonymous self-administered questionnaire survey was conducted regarding demographics, nutritional status, and social isolation. Nutritional status was evaluated using the Mini Nutritional Assessment(®)-Short Form (MNA(®)). Combining "at risk for malnutrition" and "malnutrition," the status was classified into two groups: "normal nutrition" and "at risk for malnutrition." Social isolation was examined using the Japanese version of the abbreviated Lubben Social Network Scale (LSNS-6), which was divided into isolation (less than 12 points) and non-isolation (more than 12 points). Multivariate logistic regression analyses were conducted to assess association between malnutrition and isolation by adjusting for the following possible confounders: age, sex, living alone, self-rated economic conditions, housebound, loneliness, eligible for Long-Term Care Insurance, and the Tokyo Metropolitan Institute of Gerontology (TMIG) Index of Competence. Among 343 respondents (77.6%), the number of valid responses was 288 (65.2%)-121 men and 167 women. The average age was 74.7±6.1 years old (mean±standard deviation), ranging from 65 to 98. Based on the LSNS-6, social isolation was encountered in 44.1%. According to the MNA(®) classification, 171 (59.4%) were classified as "normal nutritional status," 108 (37.5%) as "at risk for malnutrition," and 9 (3.1%) as "malnutrition." "At risk for malnutrition" and "malnutrition" were found in 40.6% in this study. Multivariate logistic analyses showed that risk factors for malnutrition were social isolation (OR=2.52, 95% CI; 1.44-4.41) and poor economic conditions (OR=1.98, 95% CI; 1.15-3.41). Significant interaction between age and living alone suggested that elderly individuals over 75 years of age who live alone were also at risk for malnutrition. This study revealed that malnutrition of elderly individuals was associated with social isolation and poor economic conditions as well as age over 75 and living alone. Malnutrition and social isolation can be prevalent in elderly residents of city public housing facilities. Measures of social isolation as well as nutritional support are necessary for health promotion and preventive care of the elderly.

Filling the Meso-Level Gap in Stratification Theory.

Filling the Meso-Level Gap in Stratification Theory.

Relation between the loneliness levels and cognitive deviation of medical students and its influ-encing factors

Objective To examine the interrelation between the cognitive deviation and loneli-ness levels of medical students and its influencing factors. Methods Totally 220 medical students in grade two of one medical school were selected by method of cluster random sampling. The data of the research were obtained through cognitive bias questionnaire （CBQ） and emotional-social loneliness questionnaire. Interrelation between the cognitive deviation type and condition of emotional-social lone-liness of medical students were analyzed by Pearson product-moment correlation two-tailed test. Multi-ple stepwise regression analysis was conducted by taking score of emotional-social loneliness as de-pendent variable and score of CBQ as independent variable. Differences in cognitive deviation and loneliness levels between rural and urban students as well as between students from single child family and students from non single child family were analyzed by independent-sample t test. Results Neg-ative cognitive deviation of depression-distortion type was positively correlated with medical students’ emotional isolation （r=0.161, P=0.021）,social isolation （r=0.266,P=0.000）, emotional loneliness （r=0.340, P=0.000） and social loneliness （r=0.385, P=0.000）. The regression equation was： score of emotional-social loneliness=27.165＋1.908 （depression-distortion）＋0.836 （depression-non distortion）.Students from non single child family had higher scores than students from single child family in the perspectives of depression-distortion”（P=0.017）, social isolation（P=0.001）, emotional loneliness（P=0.016）, social loneliness（P=0.000）. Rural students had higher scores in the above four perspectives than urban students（P〈0.05）. Conclusions Negative cognitive deviation levels of medical students is positively correlated with emotion and social isolation conditions and loneliness experiences. Regres-sion analysis shows that unhealthy cognitive disposition and thinking mode probably are one of the im-portant reasons leading to medical students’ stress disorder. Students from single child family and rural area may experience social loneliness more deeply and students from single child family have obvious cognitive deviation. Key words: Cognitive deviation; Loneliness; Correlation analysis

Cronobiologia e inclusão educacional de pessoas cegas: do biológico ao social

Estudos sobre inclusão educacional têm apontado alguns caminhos para garantir a inserção da pessoa com deficiência no espaço regular de ensino. Entretanto, pouco se tem falado a respeito das implicações do ritmo circadiano na inclusão da pessoa totalmente cega nesse espaço. Assim, o presente artigo teve como objetivo descrever como o ritmo circadiano pode influenciar na inclusão educacional do aluno com deficiência visual. A partir da revisão literária foram apresentadas as ideias fundamentais a respeito da cronobiologia, ciência que estuda a capacidade dos seres vivos em expressar de forma recorrente e periódica o seu comportamento e a sua fisiologia. Uma de suas expressões tem uma duração próxima há 24 horas, conhecido como ritmo circadiano. Esse ritmo é regido pelo relógio biológico que é controlado pela luz. Entretanto, na ausência da luz, caso de pessoas totalmente cegas, quem passa a reger os ritmos circadianos é apenas o relógio biológico. Nessa condição, conhecida como livrecurso, as pessoas totalmente cegas podem apresentar uma queda no desempenho acadêmico de tempos em tempos por causa da sonolência excessiva durante as horas de estudo, além de distúrbio no humor, no alerta e na atenção. Neste contexto, se faz necessário a divulgação desse conhecimento para que sejam reconhecidas as condições de déficit de atenção, irritabilidade, isolamento social e/ou sonolência excessiva durante o dia, oriundas do livre-curso afim de respeitar a individualidade dos alunos totalmente cegos e garantir o acesso à inclusão educacional em sua completude.

The effect of social buffering on fear responses in sheep (Ovis aries)

Fear in farm animals has been extensively studied because of its close relation to animal welfare. Numerous studies have categorized the behavioral responses of animals to stimuli that can elicit a fear reaction under social isolation conditions. However, farm animals are highly social and therefore these responses could be conditioned by isolation. The objective of this study is to evaluate the potential buffering effect of the social environment on the fear responses of sheep, comparing the reactivity of individuals within different social environments. We studied the reactivity of 15 ewes (focal individuals) in isolation, and within groups composed of 5 and 10 individuals, randomly alternating the presence of a sudden stimulus with a normal, non-stimulus situation (control). The XY coordinates and the behavior of each focal individual (inactivity, exploration, fast movements, attempt to escape, filial interactions, agonistic interactions, and other activities) were recorded, at 1min intervals during tests lasting 15min, using the Chickitizer software. Euclidean distances were subsequently obtained, and total traveled distance, net distance, minimum distance, maximum distance, and path sinuosity (ND/TD) calculated. Results show a significant effect of both the presence/absence of stimulus and the group size on the distance measures, exploration and filial interactions (P≤0.01). Moreover, the buffering effect of group size was demonstrated by the lower incidence of fast movements (P<0.001) and escape attempts (P<0.001). The interaction between the presence/absence of stimulus and the group size was significant for inactivity (P=0.001). Results show a marked effect of the stimulus presence, regardless of group size. However, stress reactions due to social isolation were substantially greater than those elicited by the mere presence of the stimulus. These results highlight the importance of the management procedures, particularly when animals need to be isolated from the group.

Call of the Wild: The Negative Tendency in the Nature Religions of American Youth

The author argues that the paucity of options for sanctioned rebellion in contemporary American society drive an ever-increasing number of idealistic youth in search of isolation in nature, where they construct what the author here calls "nature religions." These worldviews focus on purification of falsehood, ritualized through enduring extreme physical pain, social isolation, and extreme weather conditions in hopes of experiencing reality more authentically. The author argues that unemployment, limited vocational options, and the homogenization of American society are among the major catalysts for this ever-expanding breed of seekers, each of whom struggles with a negative tendency (a theoretical term created by Erik Erikson). Furthermore, the author argues that the emphasis in the nature religions on connection to nature is constructed to compensate for the lack of community and sense of human connectedness in contemporary American society. A representative case study from Jon Krakauer's (Into the wild; Doubleday, New York, 1996) Into the Wild is presented to illuminate and justify the argument made by the author for more institutionally housed options for sanctioned, licit rebellion to manage the negative tendency.

1581 – Steroid hormones levels in alcohol dependent patients under conditions of social isolation

According to literature data, steroid hormones are involved in development of aggressive behavior. In addition, it is shown that alcoholism is associated with alterations in the activity of hypothalamic-pituitary-adrenal axis during chronic alcohol consumption and in withdrawal period as well. Objective The research aims to investigate the correlations between steroid hormones level alterations and aggression level among alcoholic patients under conditions of social isolation. Material and methods Serum levels of cortisol and testosterone were measured in alcohol dependent males with aggressive behavior (n=60) and in alcohol-dependent non-aggressive males (n=27) being under conditions of social isolation. The control group consisted of 24 alcoholic patients during alcohol withdrawal. The hormone serum levels were measured with ELISA method. Statistical processing of results was carried out with software package SPSS for Windows. Results In comparison with the control group, increase of cortisol concentration in patients under conditions of social isolation has been observed. Patients with aggressive behavior have shown the trend toward cortisol level increase as against nonaggressive alcohol-dependent males. Concentration of testosterone in the investigated groups did not differ from the one of control group. Conclusions Increase of cortisol level in the investigated groups is apparently a consequence of influence of the factor of social isolation, but also it might be associated with aggressiveness tendency of alcoholic patients. Steroid hormones may play a significant role in aggressive behavior of alcohol-dependent patients in the conditions of social isolation.

Prior housing conditions and sleep loss may affect recovery from brain injury in rats: A pilot study

The purpose of this study is to understand the effect of combat-associated conditions such as sleep deprivation (SD) on subsequent traumatic brain injury (TBI). Prior to TBI (or sham surgery) induced by controlled cortical impact (CCI), rats were housed singly in chambers that prevented rapid eye movement sleep or allowed unrestricted sleep (no SD). Sensorimotor function was tested pre-SD and retested on postoperative days (PDs) 4, 7, and 14. Two additional control groups were housed socially prior to either CCI or sham surgery. CCI resulted in immediate performance deficits on sensorimotor tasks. The PD on which performance returned to baseline depended on preinjury conditions. Overall, preinjury SD+CCI resulted in an earlier recovery than no SD+CCI, and the no SD+CCI group (housed singly under conditions comparable with the SD group) recovered slower than all other groups. These data are the first to raise the possibility that recovery of sensorimotor function following TBI is affected by preinjury conditions. The data suggest that preinjury SD 24 h in duration may result in faster recovery and that novel or social isolation conditions may impede recovery. Thus, the combat environment may contribute to complexities associated with TBIs common in U.S. servicemembers.

Asymmetry in the content of brain monoamines of BALB/c mice reared in social isolation conditions

The effects of long-term social isolation on the content and metabolism of dopamine and serotonin systems were studied in symmetrical brain structures of BALB/c male mice. With HPLC the contents of dopamine (DA), serotonin (5-HT) and their metabolites dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindolacetic acid (5-HIAA) were measured in the cortex, hippocampus and striatum of both the right and the left hemispheres of the brain in mice reared in groups and social isolation. The isolated mice were characterized by reduced level of DA in the left striatum and elevated level of 5-HIAA and ratio 5-HIAA/5-HT in the right striatum. In the hippocampus of isolated mice, the activation of both DA-ergic and 5-HT-ergic systems was observed, that is the high level of DA and DOPAC in the left hippocampus and the elevated level of 5-HT in both hemispheres and of 5-HIAA in the right hippocampus were registered. On the other hand, the reduction of both DA-ergic and 5-HT-ergic systems activity was shown to be in the right hemisphere. The decreased concentration of DOPAC and ratio DOPAC/DA in the right cortex were observed as well. As to 5-HT-ergic system, the reduced level of 5-HT in the both cortex of the hemispheres as well as 5-HIAA in the right hemisphere of isolated mice was determined. The phenomenon of interhemispheric asymmetry was revealed in the hippocampus only, which was characterized by the increased DA-ergic activity in the left hippocampus but not in the striatum and the cortex.

Adolescent Rearing Conditions Influence the Relationship Between Initial Anxiety‐Like Behavior and Ethanol Drinking in Male Long Evans Rats

Rodent studies have demonstrated that adolescent social isolation results in many behavioral perturbations, including increases in anxiety-like behaviors. Socially isolated (SI) rats have also been shown to self-administer greater amounts ethanol (EtOH) in some, but not all, studies. Here, we tested whether juvenile social isolation increases EtOH drinking using an intermittent procedure that engenders relatively high intake in normally reared animals. We also compared the behavioral phenotype of rats reared under social isolation or group-housed conditions with adult rats housed under conditions commonly used in EtOH-drinking studies. Male Long Evans rats were procured immediately postweaning and were group housed for 1 week. Subjects were then randomly divided into 2 groups: SI rats, housed individually for 6 weeks and group-housed (GH) rats (4/cage). A third group was procured as young adults and was housed individually upon arrival for 1 week (standard housing condition). Rats were then tested in a plus-maze and novelty assay, and then, all subjects were singly housed and EtOH drinking was assessed. SI rats displayed increased anxiety-like behaviors on the plus-maze, a greater locomotor response to a novel environment, and increased EtOH intake, relative to GH rats. Age-matched standard housed (STD) rats exhibited an anxiety-like behavioral profile on the plus-maze that was similar to SI, and not GH rats, and also drank EtOH at levels comparable with SI subjects. In addition, anxiety-like behavior on the plus-maze correlated with intermittent EtOH intake in SI and GH rats. These data further support the validity of the rodent juvenile social isolation model for studies directed at elucidating behavioral and neurobiological mechanisms linking anxiety and EtOH drinking. These findings further suggest that housing conditions commonly employed in rodent drinking studies may recapitulate the anxiety-like and EtOH-drinking phenotype engendered by a juvenile social isolation procedure.

24-Hour Autonomic Dysfunction and Depressive Behaviors in an Animal Model of Social Isolation: Implications for the Study of Depression and Cardiovascular Disease

To investigate the hypothesis that long-term social isolation in an animal model would produce depression-relevant behaviors and disruptions in the 24-hour autonomic and activity parameters, and to further demonstrate the utility and validity of an animal model for the study of social environment, behavior, and autonomic function. Converging evidence from both experimental and epidemiological studies indicates that there is a bidirectional association between depression and cardiovascular disease; however, the precise neurobiological mechanisms underlying this relationship are not well understood. Disruptions in the social environment may influence this relationship. Depression-relevant behaviors and ambulatory electrocardiographic and activity data were measured in 12 adult, socially monogamous prairie voles (rodents) during a period of chronic social isolation or social pairing (control conditions). Prairie voles exposed to 4 weeks of social isolation versus control conditions (social pairing) exhibited anhedonia, increased 24-hour heart rate, reduced 24-hour heart rate variability, and predictable correlations between the behavioral measure (anhedonia) and the autonomic measures. Social isolation is associated with depressive behaviors, 24-hour autonomic dysfunction, and predictable interrelationships between these variables in prairie voles but does not seem to be associated with rhythmicity changes in activity level or autonomic function. These findings have implications for understanding the role of the social environment in mediating the association of mood and cardiovascular disorders in humans.