Social isolation, where a person has little actual interaction with others, more so than loneliness, a subjective feeling that one’s social connections fall short of what we desire or need, is tied to premature death in older people.

This was the finding of a new study led by epidemiologist Andrew Steptoe of University College London and colleagues that was published in the Proceedings of the National Academy of Sciences this week.

This surprising result suggests that even people who are happy in their solitude, if they don’t have enough human contact, they are more likely to die prematurely.

There is evidence that both social isolation and loneliness are tied to increased risk of premature death, but researchers are struggling to show whether these factors act independently or together.

To try and tease these apart, researchers like Steptoe and colleagues address some interesting questions, such as:

Is a person who likes being socially cut off in their “voluntary solitude”, in the same boat when it comes to risk of premature death as a person who is more socially connected but nevertheless feels very lonely?

For their latest study, Steptoe and colleagues assessed social isolation in in 6,500 men and women aged 52 years and over.

They measured social isolation in terms of amount of contact with family and friends, and participation in religious and other organized groups.

The participants had been recruited to take part in the English Longitudinal Study of Ageing in 2004 – 2005 where they had also filled in questionnaires relating to a standard measure of loneliness.

The researchers followed the participants for an average of 7.25 years (up to March 2012) and noted any who died in that period.

When they analyzed the results from the loneliness and social isolation measures together with the mortality rates, they found that deaths were higher among the more socially isolated and also among the more lonely participants.

However, after statistically adjusting the figures to take into account possible influencing factors (such as age, health, income and education), social isolation remained significantly tied to premature death but loneliness did not.

The most socially isolated participants had a 26% higher risk of dying.

They then tried to work out if the link to death was due to the fact that isolated people are often lonely; but they found it didn’t work like that.

“The association of social isolation with mortality was unchanged when loneliness was included in the model,” they note.

So the researchers conclude that loneliness is closely bound up with other potential influencing factors, and it does not contribute to the effect of social isolation, leading them to recommend:

“Although both isolation and loneliness impair quality of life and well-being, efforts to reduce isolation are likely to be more relevant to mortality.”

Speculating on what the reasons might be for this significant link the researchers suggest perhaps older people with few social connections don’t receive some of the vital elements of care, such as having someone encouraging them to eat properly, or reminding them to take their medication, or giving a helping hand when they need one.

It seems that what this study is saying is that even though there are people who are happy to remain socially isolated, we should still look out for them, and make sure they receive timely advice and support.

The study adds to the ongoing debate about whether lack of social contact, an objective condition, or the more subjective, emotional state of loneliness, or some combination of the two, shortens lifespan.

However, it far from resolves the debate, as Bert Uchino, a health psychologist at the University of Utah in Salt Lake City, tells Science NOW.

Uchino says the study is a good one, it has a large sample size, and compares social isolation directly with loneliness, but it does not really help us understand how the two factors relate either to one another or to other factors that affect health.

“I just don’t think it’s going to be the final word on the issue,” he adds.

John Cacioppo, a psychology professor at the University of Chicago in Illinois, says the discrepancy between this study and the work he has done, which suggests there is a link between loneliness and a higher rate of premature death in older Americans, could be due to cultural differences between Americans and British older people.

This could cause them to answer questionnaires differently and define friends differently too, says Cacioppo.

Another problem that researchers working in this area sometimes raise is that the more we study loneliness, the more it appears to be easier to describe than to define.

Written by Catharine Paddock PhD