“In humans, loneliness involves an implicit hyper-vigilance for social threat”.
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Now researchers at the University of Chicago and the University of California have discovered that loneliness actually triggers physical responses in the body which make people sick. Their study, published in the Proceedings of the National Academy of Sciences, showed that lonely people had a less effective immune response and more inflammation than non-lonely people involved in the study.
Research shows loneliness leads to fight-or-flight signalling occurring in the body, which can lead to a drop in white blood cells for over a year weakening the immune system. They’ve found the same effect as in their previous study, that loneliness causes an increased gene expression for inflammation while the gene expression for the immunes system’s fight against antiviral infections is decreased. This indicates that leukocyte gene expression and loneliness work together to exacerbate each other over time.
The latest study confirmed these previous findings, but also highlighted the chance that loneliness could predict future CTRA gene expression more than one year later. The conserved transcriptional response to adversity may be an evolutionary adaptation that eliminates an individual that is not a productive social member of society either through choice or circumstance.
Loneliness has a measurable impact on the part of the immune system responsible for fighting infections and cancer according to a study that could help to explain why people suffering from social isolation are 14 per cent more likely to suffer an early death compared to people who are not lonely.
In another study, the team investigated the cellular processes linking social experience to CTRA gene expression in rhesus macaque monkeys. This response is characterized by an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses.
But the study also showed several important new pieces of information about loneliness’ effect on the body. Like the lonely humans, the “lonely like” monkeys showed higher CTRA activity.
The team found that both lonely monkeys and humans had higher levels of monocytes in their blood.
They found the same shift in genetic expression in the white blood cells of people who lived alone and in social isolation.
They were also found to have higher levels of noreprinephrine, a “fight-or-flight” neurotransmitter that stimulates the production of immature monocytes, a white blood cell with high inflammation/low antiviral defense gene expression.
In the monkeys, the scientists found that these pro-inflammatory changes in gene expression had real consequences for the monkeys’ health.
The researchers also showed that, in monkeys at least, the lonliness changes allowed simian immunodeficiency virus (the monkey version of HIV) to grow faster in both blood and brain.
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“The resulting shift in monocyte output may both propagate loneliness and contribute to its associated health risks”.
