Loneliness is worse for ageing than smoking, scientists have found, after discovering that people who feel isolated are nearly 20 months older than their chronological age.
A team of international researchers discovered a startling link between mental well-being and the tell-tale signs of ageing in the blood and body.
Having a poor psychological state, which included feeling lonely, depressed, hopeless or sad, increased biological age by nearly 20 months, compared to smoking regularly, which raised age by 15 months.
Living in a rural area also increased ageing markers by 0.39 years, compared with urban dwellers, while never marrying aged people by 0.32 years.
Professor Helene Fung from The Chinese University of Hong Kong and the lead contributor to the research, said: “For decades, people have thought that they can maintain their well-being – and organisations think that they can increase their productivity – by working on the biological health of themselves and their employees, such as providing medical checkups.
“Yet, our findings suggest that working on psychological factors, such as maintaining a positive mood, can be equally important.”
Chronological vs biological age
The team, which included researchers from Stanford University and the research group Deep Longevity, measured biological age using a blood test which looks for 16 biomarkers of ageing, as well as data such as blood pressure, heart rate, waist circumference and lung function.
Blood biomarkers included glucose and cholesterol levels, cystatin C which shows renal function, and creatinine which is a sign of kidney function.
The team carried out the test on 4,451 Chinese participants to find out how their chronological age differed from their biological age.
Previously the team has shown that people with a higher biological age than their chronological age are more likely to suffer health-related conditions, such as ovarian cancer, irritable bowel diseases, and multiple sclerosis.
Researchers said there was an important takeaway message that biological ageing can be substantially influenced by psychological factors such as feeling lonely or unhappy, and the magnitude of those influences can be as high as that of smoking and serious diseases.
Manuel Faria of Stanford University said.“I hope that this research plants a seed for further clinical applications.
“I foresee that longitudinal psychometric analyses will be an integral part of primary care in the future.”
‘Fight or flight’
Previous studies have found that social isolation is a major health problem that can increase the risk of premature death by 14 per cent.
In 2015, the universities of California and Chicago found that loneliness can trigger genetic changes which cause illness and early death.
Feeling alone 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.
Both lonely humans and monkeys showed higher levels of monocytes – immune cells – in their blood.
Earlier this year, the University of Cambridge found that social isolation may shrink the brain and increase the risk of developing dementia.
The research suggested that the brain withers without stimulation from friends, family and co-workers, leading to neurodegeneration.