Loneliness poses a serious risk to the health of older people

Loneliness is no longer just an emotional factor and has been identified as being a key factor in premature deaths in older people.

A new study, led by researchers at the University of Chicago and the University of California has supported previous research which indicated that loneliness has the potential to increase the risk of premature death in older people by 14 per cent as they have lower levels of white blood cells in their body.

This new research allows scientists to identify the specific triggers that cause the phenomenon.

The report is published in the Proceedings of the National Academy of Sciences (PNAS). Led author of the study and psychologist, John Cacioppo writes: “Perceived social isolation (PSI) (loneliness in humans) is a risk factor for chronic illness and all-cause mortality but the molecular mechanisms of its health effects remain poorly understood.

“In humans, PSI involves an implicit hypervigilance for social threat.”

Researchers identified that feelings of loneliness appeared to prompt a ‘fight or flight’ reaction, though reactions were found to be dependent on individual factors, including: stress and depression and social support.

Scientists observed gene expression in leukocytes, cells which are responsible for protecting the human body against bacteria and viruses. The research supports a previous study linking loneliness with a phenomenon called ‘conserved transcriptional response to adversity’ (CTRA).

CTRA sees people who are lonely or living in solitude have an increased level of activity in all genes which create inflammation in the body. This leads to people who experience loneliness having a decreased immune response and more gene inflammation, making them more susceptible to illness than people who are not lonely.

Researchers said: "Leukocyte gene expression and loneliness appear to have a reciprocal relationship, suggesting that 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.”

Scientists further identified that loneliness and leukocyte gene expression had the potential to provoke a reaction in 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 risks associated with social isolation loneliness are well known, but the effects that loneliness can have the body have not been previously understood.

Scientists studied the sociable primates, rhesus macaques and identified similar cell processes linked to their social experiences.

Similar to lonely humans, ‘lonely-like’ monkeys showed an increase in CTRA activity and higher levels of the ‘fight or flight’ neurotransmitter, norepinephrine. In addition they had increased gene express and reduced levels of antiviral defences.

Researchers added: "Both lonely humans and 'lonely like' monkeys showed higher levels of monocytes in their blood.

"The 'danger signals' activated in the brain by loneliness ultimately affect the production of white blood cells.

"The resulting shift in monocyte output may both propagate loneliness and contribute to its associated health risks."