A groundbreaking study confirmed, for the first time, that loneliness triggers biological changes that make people ill. Loneliness disrupts production of white blood cells by triggering the "fight or flight" response. It also increases the activity of genes responsible for inflammation and lowers the activity of genes accountable to fighting off illness.
Researchers from the University of California and University of Chicago found that lonely people's immune responses is less effective compared to non-lonely people. In comparison, lonely people also have increased body inflammation. They also feel threatened in a social manner, which affects their health tremendously.
"Perceived social isolation is a risk factor for chronic illness and all-cause mortality but the molecular mechanisms remain ill understood. In humans, loneliness involves an implicit hyper-vigilance for social threat," said John Capitanio from the University of California.
The researchers analyzed the effect of loneliness in humans and a highly social type of primate species, the rhesus macaque. A past research involving the two species found a link between loneliness and a biological phenomenon called conserved transcriptional response to adversity (CTRA). The phenomenon's identifying factors are the increased activity in genes responsible for inflammation and decreased activity in genes responsible for antiviral reactions.
The cumulative findings showed that loneliness affects the "fight or flight" response, which then increases production of immature monocytes in the blood. High levels of monocytes increases the activity of inflammatory genes. Increased monocytes' presence in the blood lowers the activity of genes responsible for fighting off viruses and bacteria. The blood of lonely macaques and humans showed high levels of monocytes. Monkeys who were continually thrusted into slightly stressful situations such as new and unfamiliar cage-mates showed increased levels of monocytes.
Loneliness activates "danger signals" in the brain which disrupts healthy production of white blood cells. Heightened monocyte production may intensify loneliness and influence health risks.
The next disturbing effect they found is the increased levels of norepinephrine, the "fight or flight" neurotransmitter, in lonely macaques. Past research explained that norepinephrine triggers bone marrow's blood stem cells to create more immature monocytes. The increased production of immature monocytes explained the heightened CTRA activity in the white blood cell pool.
They also discovered that loneliness can predict CTRA activity one year or further into the future and vice versa. The findings were definite to loneliness and are not connected to other forms of dangers like stress and depression.
The research team is pushing forward to discover how loneliness can lead to poor health conditions and how it can be intercepted in senior adults.
The study was published in the Proceedings of the National Academy of Sciences journal.
