We all know that social connectedness positively affects quality of life and well-being. However, not everyone is aware of how profound these effects are. Being socially connected is not only influential for psychological and emotional well-being, but it also has a significant and positive influence on physical well-being. On the other hand, social isolation — one of the invisible epidemics — is linked to an increased risk for chronic diseases and early mortality. Mother Theresa once said: “The biggest disease today is not leprosy or cancer or tuberculosis, but rather the feeling of being unwanted, uncared for and deserted by everybody.”
Notice how the previous quote subtly emphasizes “loneliness” — the feeling of — as compared to “social isolation”. Social isolation is the lack of social interaction, contact, or communication with other people. Those who socially isolate have an absence of relationships with family and friends, or other forms of social networks. Social isolation may be expressed through physical separation with others, social barriers, or psychological mechanisms. Loneliness, as explained by John Cacioppo, has a lot in common with pain, hunger, and thirst, and is a subjective emotional state — it is the perception of social isolation — “You can feel isolated in a crowd. You can also choose to be alone and feel blissful solitude. When people feel others around them are threats rather than sources of cooperation and compassion, they feel socially isolated, lonely.”
Results from a recent meta-analysis, which analyzed data collected from 70 independent published health studies and more than 3.4 million people from 1980 to 2014, show that the influence of both objective and subjective social isolation on risk for mortality is even higher than well-established risk factors for mortality, as for example smoking and obesity. Julianne Holt-Lunstad, lead author of the study, told the New York Times: “The key point that I hope others will get from this is the recognition that this is an important public health issue. Social isolation significantly predicts risk for premature mortality comparable to other well established risk factors. Thus, we need to take our social relationships as seriously for our health as we do these other factors.”
Loneliness is a complex trait, likely influenced by variations within multiple genes — especially genes related to neurotransmitters and the immune system — and their interaction with numerous behavioral and environmental factors. Such factors, as for example low social support, may have a more pronounced effect and lead to higher levels of loneliness if individuals carry the sensitive variant of these genes.
Not surprisingly, then, results from a study published a few days ago by an interdisciplinary team of researchers (November 23, 2015) in the scientific journal Proceedings of the National Academy of Sciences show that loneliness triggers cellular changes caused by fight-or-flight stress responses that increase the chances of getting ill by affecting the immune system. The “danger signals” activated in the brain by feelings of social isolation and loneliness affect the production of white blood cells (leukocytes), the major component of the immune system. For the study, an interdisciplinary group of researchers examined loneliness in both humans and rhesus macaques, a highly social primate species.
Previous research from the same team had identified a link between loneliness and a phenomenon called “conserved transcriptional response to adversity” or CTRA. This response is characterized by an increased expression of genes involved in inflammation, and a decreased expression of genes involved in antiviral responses. In other words, loneliness up-regulates potentially detrimental inflammatory responses, and down-regulates beneficial, protective immune responses.
For the current study, researchers examined gene expression in leukocytes of humans and macaques. Their findings show CTRA effects, and suggest that increased activity of the sympathetic nervous system, which is responsible for the “fight or flight” response, may overstimulate development of monocytes — inflammatory leukocytes — in the bone marrow. At the same time, there is decreased production of the antiviral proteins Type I and II interferons — such decrease may reduce the body’s ability to fight infections. Reduction of the body’s ability to fight infections is confirmed by the impaired response to infection by simian immunodeficiency virus (SIV) observed in macaques, which allowed SIV to grow faster in both macaque blood and brain. SIV is the macaque equivalent of the human immunodeficiency virus (HIV).
The study results also suggest that leukocyte gene expression and loneliness have a reciprocal relationship — each can help propagate the other over time. These results were specific to loneliness and could not be explained by depression, stress or social support.