Social isolation

In the first resting state fMRI functional connectivity (FC) study on PSI,[6] PSI was found to be associated with increased resting-state FC between several nodes of the cingulo-opercular network, a neural network associated with tonic alertness. PSI was also associated with reduced resting-state FC between the cingulo-opercular network and the right superior frontal gyrus, suggesting diminished executive control. Cacioppo and colleagues (2009)[3] found that lonely individuals express weaker activation of the ventral striatum in response to pleasant pictures of people than of objects, suggesting decreased reward to social stimuli. Lonely individuals also expressed greater activation of the visual cortex in response to unpleasant depictions of people (i.e., negative facial expressions) than of objects; non-lonely individuals show greater activation of the right and left temporoparietal junction (TPJ), a region implicated in theory of mind. The authors interpreted the findings to represent that lonely individuals pay greater attention to negative social stimuli, but non-lonely individuals, to a greater degree than lonely individuals, insert themselves into the perspective of others. Moreover, Kanai et al. (2012) reported that loneliness negatively correlated with gray matter density in the left posterior temporal sulcus, an area involved in biological motion perception, mentalizing, and social perception.[7]

Overall, several neuroimaging studies in humans on perceived social isolation have emphasized implications of the visual cortex and right-hemispheric stress-related circuits underlying difference between lonely and non-lonely individuals. A recent population-genetics study marked a 50x increase in the neuroimaging research on perceived social isolation. The investigators tested for signatures of loneliness in grey matter morphology, intrinsic functional coupling, and fiber tract microstructure. The loneliness-linked neurobiological profiles converged on a collection of brain regions known as the default mode network. This higher associative network shows more consistent loneliness associations in grey matter volume than other cortical brain networks. Lonely individuals display stronger functional communication in the default network, and greater microstructural integrity of its fornix pathway. The findings fit with the possibility that the up-regulation of these neural circuits supports mentalizing, reminiscence and imagination to fill the social void.[8]

Social isolation contributes to abnormal hippocampal development via specific alterations to microtubule stability and decreased MAP-2 expression.[15] Social isolation contributes to decreased expression of the synaptic protein synaptophysin[16] and decreased dendritic length and dendritic spine density of pyramidal cells.[17] The underlying molecular mechanism of these structural neuronal alterations are microtubule stabilizations, which impair the remodeling and extension of axons[18] and dendrites.[19]

Research by Cole and colleagues showed that perceived social isolation is associated with gene expression – specifically, the under-expression of genes bearing anti-inflammatory glucocorticoid response elements and over-expression of genes bearing response elements for pro-inflammatory NF-κB/Rel transcription factors.[20] This finding is paralleled by decreased lymphocyte sensitivity to physiological regulation by the HPA axis in lonely individuals. This, together with evidence of increased activity of the HPA axis, suggests the development of glucocorticoid resistance in chronically lonely individuals.[21]

Social isolation can be a precipitating factor for suicidal behavior. A large body of literature suggests that individuals who experience isolation in their lives are more vulnerable to suicide than those who have strong social ties with others.[22] A study found social isolation to be among the most common risk factors identified by Australian men who attempt suicide. Professor Ian Hickie of the University of Sydney said that social isolation was perhaps the most important factor contributing to male suicide attempts. Hickie said there was a wealth of evidence that men had more restricted social networks than women, and that these networks were heavily work-based.[23]

A lack of social relationships negatively impacts the development of the brain's structure. In extreme cases of social isolation, studies of young mice and monkeys have shown how the brain is strongly affected by a lack of social behaviour and relationships.[24][25]

In a hypothesis proposed by Cacioppo and colleagues, the isolation of a member of a social species has detrimental biological effects. In a 2009 review, Cacioppo and Hawkley noted that the health, life, and genetic legacy of members of social species are threatened when they find themselves on the social perimeter.[3] For instance, social isolation decreases lifespan in the fruit fly; promotes obesity and type 2 diabetes in mice;[26] exacerbates infarct size and oedema and decreases post-stroke survival rate following experimentally induced stroke in mice; promotes activation of the sympatho-adrenomedullary response to an acute immobilisation or cold stressor in rats; delays the effects of exercise on adult neurogenesis in rats; decreases open field activity, increases basal cortisol concentrations, and decreases lymphocyte proliferation to mitogens in pigs; increases the 24-hour urinary catecholamine levels and evidence of oxidative stress in the aortic arch of rabbits; and decreases the expression of genes regulating glucocorticoid response in the frontal cortex.

Social isolation in the common starling, a highly social, flocking species of bird, has also been shown to stress the isolated birds.[27]

The following risk factors contribute to reasons why individuals distance themselves from society.[29][30][31]

• Aging – Once a person reaches an age where problems such as cognitive impairments and disabilities arise, they are unable to go out and socialize.
• Health and disabilities – People may be embarrassed by their disabilities or health problems, such that they have a tendency to isolate themselves to avoid social interaction out of fear that they would be judged or stigmatized. This is common in people who have autism and other known disorders. Sometimes, rather than embarrassment, the disability itself and a person's lack of a support network can be the cause of social isolation.[32]
• Hearing loss – hearing loss can cause communication impairment, which can lead to social isolation particularly in older adults.[33]
• The loss of a loved one can contribute to social isolation. Studies have shown that widows who keep in contact with friends or relatives have better psychological health. A study conducted by Jung-Hwa Ha and Berit Ingersoll-Dayton concluded that widows who had a lot of social contact and interactions lead to fewer depressive symptoms. During a time of loss social isolation is not beneficial to an individual's mental health.[34]
• Living alone – A 2015 study by the National Center for Family & Marriage Research found 13 percent of adults in the United States were living alone, up from 12 percent in 1990. The rate of living alone for people under 45 has not changed, but the rate for Americans aged 45 – 65 has increased over the past 25 years. People over the age of 65 are living alone less often.[35]
• Isolation may be imposed by an abusive spouse.[36]
• Rural isolation - In rural areas, factors such as living far apart from one another, rural flight, a negligible amount of public spaces and entertainment, and lack of access to mental health-related resources all contribute to isolation. Limited access to broadband internet and cellular activity also make it harder for those experiencing isolation to connect online or reach people.[37]
• Unemployment – This can begin if someone is fired, dismissed, or released from a job or workplace, or leaves one of their own accords. If the person struggles or is unable to find a new job for a long period of time (i.e. months or years) the sense of isolation can become exacerbated, especially in men.[38]
• Independent home worker – The tasks implied in this kind of job generally doesn't imply social interaction in the physical level, nor going outside. Interactions and payments can be made by digital mediums so the person remains isolated from society.
• Retirement – or other source of fixed income, makes innecessary for the person to search for a job, this situation is similar to unemployment but with better living on one hand but without the need to go outside on the other hand.
• Transportation problems – If the person doesn't have transportation to attend gatherings or to simply get out of the house, they have no choice but to stay home all day, which can lead to those feelings of depression.[39]
• Societal adversity – Desire to avoid the discomfort, dangers, and responsibilities arising from being among people. This can happen if other people are sometimes, or often, rude, hostile, critical or judgmental, crude, or otherwise unpleasant. The person would just prefer to be alone to avoid the hassles and hardships of dealing with people. Being a part of an outgroup and social categorization can also play a part in creating adverse circumstances that the individual may attempt to avoid depending on the policies and attitudes of the society.[40]
• Substance abuse can be both cause and/or effect of isolation, often coinciding with mood-related disorders, especially among those living alone[41]

Social isolation can begin early in life. During this time of development, a person may become more preoccupied with feelings and thoughts of their individuality that are not easy to share with other individuals. This can result from feelings of shame, guilt, or alienation during childhood experiences.[42] Social isolation can also coincide with developmental disabilities. Individuals with learning impairments may have trouble with social interaction. The difficulties experienced academically can greatly impact the individual's esteem and sense of self-worth. An example would be the need to repeat a year of school. During the early childhood developmental years, the need to fit in and be accepted is paramount.[43] Having a learning deficit can in turn lead to feelings of isolation, that they are somehow 'different' from others.[44]

Whether new technologies such as the Internet and mobile phones exacerbate social isolation (of any origin) is a debated topic among sociologists, with studies showing both positive correlation of social connections with use of social media[45] as well as mood disorders coinciding with problematic use.[46]

Social isolation impacts approximately 24% of older adults in the United States, approximately 9 million people.[47] The elderly have a unique set of isolating dynamics that often perpetuate one another and can drive the individual into deeper isolation.[48] Increasing frailty, possible declines in overall health, absent or uninvolved relatives or children, economic struggles can all add to the feeling of isolation.[49] Among the elderly, childlessness can be a cause for social isolation. Whether their child is deceased or they did not have children at all, the loneliness that comes from not having a child can cause social isolation.[50][51] Retirement, the abrupt end of daily work relationships, the death of close friends or spouses can also contribute to social isolation.[52]

In the United States, Canada, and United Kingdom, a significant sector of the elderly who are in their 80s and 90s are brought to nursing homes if they show severe signs of social isolation. Other societies such as many in Southern Europe, Eastern Europe, East Asia, and also the Caribbean and South America, do not normally share the tendency towards admission to nursing homes, preferring instead to have children and extended-family of elderly parents take care of those elderly parents until their deaths.[29][53] On the other hand, a report from Statistics Norway in 2016 stated that more than 30 percent of seniors over the age of 66 have two or fewer people to rely on should personal problems arise.[54][55] Even still, nearly half of all members of senior communities are at high risk for social isolation, this is especially prevalent with seniors of a lower education and within the lower economic class and compounded with diminished availability of socializing options to these lower class individuals. There has also been an observed increase in physical gait among members of these communities.[56]

Social isolation among older adults has been linked to an increase in disease morbidity, a higher risk of dementia, and a decrease in physical mobility along with an increase in general health concerns. Evidence of increased cognitive decline has been link to an increase in social isolation in depressed elderly women.[57]

The use of video communication/video calls has been suggested as a potential intervention to improve social isolation in seniors. However, its effectiveness is not known.[58]

Social isolation and loneliness in older adults is associated with an increased risk for poor mental and physical health and increased mortality.[59][60] There is an increased risk for early mortality in individuals experiencing social isolation compared to those who are not socially isolated.[61] Studies have found social isolation is associated with increased risk in physical health conditions including high blood pressure, high cholesterol, elevated stress hormones, and weakened immune systems.[62] Research also suggests that social isolation and mortality in the elderly share a common link to chronic inflammation with some differences between men and women.[63] Social isolation has also been found to be associated with poor mental health including increased risk for depression, cognitive decline, anxiety, and substance use.[59] Social isolation in elderly individuals is also associated with an increased risk for dementia.[61]

Middle school is a time when youth tend to be sensitive to social challenges and their self-esteem can be fragile. During this vulnerable time in development, supporting students' sense of belonging at school is of critical importance. Existing research[64] finds that adolescents' development of a sense of belonging is an important factor in adolescence for creating social and emotional well-being and academic success. Studies have found that friendship-related loneliness is more explanatory for depressive symptoms among adolescents than parent-related loneliness. One possible explanation is that friends are the preferred source of social support during adolescence.[65][66]

Scientists have long known that loneliness in adults can predispose depressive symptoms later in life. Lately, scientists have also seen that lonely children are more susceptible to depressive symptoms in youth. In one study, researchers conclude that prevention of loneliness in childhood may be a protective factor against depression in adulthood.[67][66] Socially isolated children tend to have lower subsequent educational attainment, be part of a less advantaged social class in adulthood, and are more likely to be psychologically distressed in adulthood.[68][25] By receiving social assistance, studies show that children can cope more easily with high levels of stress. It is also shown that social support is strongly associated with feelings of mastery and the ability to deal with stressful situations, as well as strongly associated with increased quality of life.[69][25]