Loneliness induces biological changes, causes illness and early death
Danger signals activated in brain by loneliness ultimately affect immune system, scientists claim
A study has shown that for the first time that loneliness is not just an emotional state of mind, it actually triggers genetic changes, which cause illness and early death.
The research was published in the Proceedings of the National Academy of Sciences.
Previous studies have found that social isolation is a major health problem that can increase the risk of premature death by 14 percent.
However until now, scientists have been unsure what is driving the phenomenon.
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.
It appears to trigger the ‘fight or flight’ stress signal, which affects the production of white blood cells. It also increases activity in genes, which produce inflammation in the body while lowering activity in genes, which fight off illness, promoting high levels of inflammation in the body.
Essentially, lonely people had a less effective immune response and more inflammation than non-lonely people. They feel socially threatened which has an enormous impact on health.
John Capitanio, of the California National Primate Research Centre at the University of California, Davis said: “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.”
The study examined loneliness in both humans and rhesus macaques, a highly social primate species.
They found that loneliness predicted how active the CTRA gene was, even a year later and vice versa. People who had high gene activity were still lonely after 12 months. They also showed higher levels of the fight-or-flight neurotransmitter, norepinephrine.
Previous research has found that norepinephrine can stimulate blood stem cells in bone marrow to make more of a particular kind of immune cell (monocytes) which ramps up inflammation in the body.
Both lonely humans and monkeys showed higher levels of monocytes in their blood. In an additional study, monkeys repeatedly exposed to mildly stressful social conditions such as unfamiliar cage-mates also showed increases in monocyte levels.