Multiple recent studies have found that loneliness is set to reach epidemic proportions through the Western world by 2030. Now, one of the most prominent researchers in the field suggests that it will soon outstrip obesity as a public health crisis.

Julianne Holt-Lunstad of Brigham Young University in Utah, US, prepared new research to present to the 125th Annual Convention of the American Psychological Association, held in Washington DC this month.

The work was based on a combination of two meta-analyses. The first involved 148 studies covering 300,000 people, and found that social connectedness to family or community reduced the risk of all-cause mortality by 50%.

The analysis also incorporated a further 70 studies covering 3.4 million people from North America, Australia and Europe. These studies looked at the health outcomes of people subject to social isolation, loneliness or living alone. They concluded that all three conditions – individually or in combination – increased the risk of premature death.

The risk escalation was in each study either equal to or greater than the risk posed by obesity.

“Being connected to others socially is widely considered a fundamental human need,” says Holt-Lunstad.

“It is crucial to both well-being and survival. Extreme examples show infants in custodial care who lack human contact fail to thrive and often die, and indeed, social isolation or solitary confinement has been used as a form of punishment.”

In 2015 Holt-Lunstad published a pioneering study into the health effects of loneliness. That study, in the journal Perspectives on Psychological Science, was also a meta-analysis, found that social isolation, loneliness or living alone increased the risk of premature death by, respectively, 29%, 26%, and 32%.

The study helped to change the focus from a lot of earlier research, which had tended to see loneliness as the product of some other condition, such as depression, or poverty.

One of the primary challenges for researchers in the field is that loneliness and social isolation have high individualistic expressions, so a rigorous definition of the condition is difficult. Attempts to define it by using a checklist approach have produced, often, distorted results.

“Loneliness is a subjective experience,” said social work professor Dr Mark Hughes, from Southern Cross University in Queensland, Australia in an interview earlier this year.

“It’s the feeling that you don’t have sufficient social connections. It’s an internal, emotional response to your life situation. I think measures will always be based on self-reporting of the experience of loneliness.”

Levels and degrees of experience are thus elusive, although the broad picture – that loneliness is increasing, and its public health implications are serious – are largely undisputed.

In 2016, the Australian crisis help organisation Lifeline released the results of its own survey into loneliness. It reported that as many as 80% of respondents said they had experienced significant periods of loneliness.

Perhaps significantly, 60% of respondents who said they “often” felt lonely lived with a partner, and many of them with children.

This apparently counter-intuitive finding accords with research published in 2009 which found levels of loneliness were higher in societies that were traditionally family-orientated compared to those where individualism and independence were seen as desirable virtues.

Although results vary, most studies into the public health implications of loneliness have reported that the risk of isolation increases with age. Holt-Lunstad warns that older people continue to constitute a growing proportion of the population, the situation is set to worsen.

“With an increasing aging population, the effect on public health is only anticipated to increase,” she says.

“Indeed, many nations around the world now suggest we are facing a ‘loneliness epidemic’. The challenge we face now is what can be done about it.”