Having satisfying social relationships may not only contribute to psychological wellbeing, but also to maintaining good health over the long term. Loneliness and social isolation, on the other hand, are associated with a shorter life expectancy free from chronic conditions.
This is what has been suggested by a study published in Nature Communications and conducted by a group of researchers from institutions including Fudan University in Shanghai, Tulane University in New Orleans, the Zhejiang University School of Medicine in Hangzhou, and Utrecht University in the Netherlands.
To better understand the phenomenon, the researchers identified two concepts which, although related, describe different experiences:
Thus, one can be socially isolated without feeling lonely, just as one can experience loneliness even when surrounded by people.
For some time now, loneliness and social isolation have been studied as possible determinants of health, in other words, as factors that can influence our risk of developing health problems. Today, they are considered important public health issues.
Numerous studies have associated these conditions with a greater risk of developing a range of illnesses, including chronic heart and respiratory diseases, type 2 diabetes, neurodegenerative diseases and cancers, not to mention mental health disorders such as depression and anxiety.
However, we have yet to fully understand to what extent loneliness and social isolation are associated with the number of years we live disease-free.
Doing so was the goal of this study. The researchers estimated disease-free life expectancy – in other words, the average number of years a person can expect to live without developing a specific condition.
In order to quantify the association between loneliness and social isolation and the number of years lived without developing chronic disease, the researchers examined data from 277,489 adults in the UK Biobank who were initially free from all seven health conditions taken into consideration:
The results showed that both loneliness and social isolation are associated with a lower disease-free life expectancy, an association which is especially marked in the case of depression or anxiety, with differences that vary based on the condition in question and on gender.
At age 50, women who experienced both loneliness and social isolation had an average of 2.4 fewer years lived without any of the five main physical diseases, in comparison with women experiencing neither of the two conditions. Among men, the same difference stood at 1.7 years.
The differences between the genders are more marked when it comes to mental health. In women, loneliness in conjunction with social isolation was associated with 3.7 fewer years lived without depression or anxiety; in men, that same number stood at an average of 5.8 years.
Moreover, an analysis of the individual conditions showed that loneliness had a greater impact on women than on men: women who feel “lonely” were found to have fewer years lived free from depression or anxiety (on average, 3.9 years as compared to 2.9 for men). For social isolation, however, the situation was reversed, with an estimated reduction of 3 years for men and 2 for women.
The researchers also examined the possible role of a healthy lifestyle in alleviating the associations between loneliness, social isolation, and a lower disease-free life expectancy.
Their analysis showed that there was a lesser drop in disease-free life expectancy associated with social isolation in those who had a healthier lifestyle; this connection was not confirmed for loneliness.
The reasons for these associations are not clear. One of the hypotheses put forward by the authors is that loneliness and social isolation affect physical health through, among other things, their impact on psychological wellbeing. Another possible hypothesis is linked to a shared biological component: certain genetic factors associated with loneliness are the same ones that are linked to depression.
To understand the observed differences between men and women, the researchers hypothesised that men’s psychological wellbeing may depend more objectively on practical social support, whereas, for women, emotional support may be of greater importance.
As far as the possible protective effect of a healthy lifestyle is concerned, the findings suggested that healthy behaviours act to mitigate the association between a lower disease-free life expectancy and social isolation, but the same was not true of perceived loneliness.
Among the possible mechanisms that could explain this relationship, there are psychological stress and processes of neuroinflammation, factors to explore in future studies.
Although the observational design of the study does not permit the establishment of a cause-and-effect relationship, its results underscore the importance of further exploring the link between social relationships and health, and suggest that we assess the possible role of lifestyle changes in improving the health of those who are socially isolated.