All types of social isolation can include staying home for lengthy periods of time, having no communication with family, acquaintances or friends, and/or willfully avoiding any contact with other humans when those opportunities do arise.
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)[4] 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.
[8] 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.
The investigators tested for signatures of loneliness in grey matter morphology, intrinsic functional coupling, and fiber tract microstructure.
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.
[10] Indeed, chronic social isolation in rats has been found to lead to depression-, anxiety-, and psychosis-like behaviors as well signs of autonomic, neuroendocrine, and metabolic dysregulation.
In another example, a study found that social isolation in rats is associated with increased brain-derived neurotrophic factor (BDNF) expression in the prefrontal cortex.
[14] The effects of experimental manipulations of isolation in nonhuman social species has been shown to resemble the effects of perceived isolation in humans, and include: increased tonic sympathetic tone and hypothalamic-pituitary-adrenal (HPA) activation and decreased inflammatory control, immunity, sleep salubrity, and expression of genes regulating glucocorticoid responses.
Social isolation contributes to abnormal hippocampal development via specific alterations to microtubule stability and decreased MAP-2 expression.
[18] The underlying molecular mechanism of these structural neuronal alterations are microtubule stabilizations, which impair the remodeling and extension of axons[19] and dendrites.
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.
[23] 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.
Everyday aspects of this type of deep-rooted social isolation can mean: The following risk factors contribute to reasons why individuals distance themselves from society.
[1][54] Increasing frailty, possible declines in overall health, absent or uninvolved relatives or children, economic struggles can all add to the feeling of isolation.
[56][57] Retirement, the abrupt end of daily work relationships, the death of close friends or spouses can also contribute to social isolation.
[31][59] 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.
[69] 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.
[70] Social isolation has also been found to be associated with poor mental health including increased risk for depression, cognitive decline, anxiety, and substance use.