Is There a Link Between Social Isolation and Inflammation?
What the science on social isolation and loneliness does and does not reveal.
Posted Jul 02, 2020
Staying socially isolated for long periods of time affects all aspects of our well-being. Feeling lonely and actively staying away from others can take a heavy toll on our mental health and emotions. However, new research has started asking questions about the extent to which social isolation impacts our bodies and physical health.
Dr. Kimberley Smith, Ph.D., is a Lecturer in Health Psychology at the University of Surrey. Her areas of specialisation include ageing well with long-term conditions and better understanding the link between loneliness, social isolation, and health.
JA: How did you first get interested in this topic?
KS: I have always had an interest in the link between mental health and physical health. Particularly how depression is linked with health outcomes and bodily inflammation. However, it was my first lectureship that led me to become interested in loneliness and social isolation. This lectureship was at Brunel University London, and it was here that I met one of the world’s foremost experts in loneliness in older adults: Professor Christina Victor. I saw Christina give a talk on her work, and I found it fascinating. It got me wondering if loneliness might be linked with some of those same health outcomes that I had been looking at with depression. I remember meeting with Christina to discuss the ideas I had, and from there we started working on a series of projects on loneliness and health, including this paper. Alongside loneliness (the subjective experience of being alone) I also felt it would be interesting and useful to look at social isolation (the objective experience of being alone).
JA: What was the focus of your study?
KS: We did a type of literature review called a systematic review. A systematic review tries to find every published piece of work that has answered the same question. We wanted to find all papers that measured the link between either loneliness with inflammation or social isolation with inflammation. We looked for markers of long-term inflammation (rather than acute inflammation) because these are linked with poorer health. To find all the studies that had answered these questions we looked through five scientific databases, the bibliographies of other papers, and abstracts that had been presented at different scientific meetings. From 7,400 initial studies, we were able to narrow down to 14 studies that had measured loneliness and inflammation and 16 that had measured social isolation and inflammation. To combine the results from these different studies we did something called a meta-analysis, which allows you to combine all of the results of papers that have asked the same question to get one overall statistic that tells you the answer to your question.
This process is not for the faint-hearted, it took us 2.5 years from doing the initial searches to finalising the paper for publication!
JA: What did you discover in your study?
KS: In short, we found that as people become more socially isolated, their levels of two markers of inflammation increase. These two markers were C-reactive protein and fibrinogen. C-reactive protein is a general marker of overall bodily inflammation, and fibrinogen is a protein that increases blood clotting.
We didn’t really find any convincing evidence linking loneliness with any of the markers of inflammation that we looked at. There was a link with an inflammatory marker called Interleukin-6, but that was only based on two studies, so it wasn’t a conclusive finding.
Interestingly, we also found that a lot of the studies we looked at had issues that limited how reliable these findings might be. Most studies were cross-sectional and measured everything at the same time. This means that even though we found social isolation and inflammation were linked, we can’t definitively say what leads to what. So, it is possible that social isolation leads to bodily inflammation, but also very possible that bodily inflammation also leads to social isolation.
Another problem was that a lot of the studies also didn’t account for important factors that might influence their measurement of inflammation, so this also meant we are limited in how much we can say about our findings.
JA: Is there anything that surprised you in your findings, or that you weren't fully expecting?
KS: I was surprised at the lack of evidence linking loneliness with inflammation. Every expert in this field talks about the fact that loneliness and inflammation are directly linked, but our review has shown that when we look at all current evidence together, there is not much evidence for a link. Another surprising finding came from one of the subgroup analyses that we did; we found that the link between social isolation and inflammation was observed in males but not females. While that was an exploratory finding I think it could be really interesting to look more in-depth at the link between social isolation and health in males in the future.
I was also surprised at the lack of long-term evidence that had been done in this field. Pretty much all the studies we included were cross-sectional and so for us to really be able to know if loneliness or social isolation causes higher inflammation, we need a lot more long-term studies.
JA: How might readers apply what you found to their lives?
KS: Based on the quality of evidence we examined, and the fact these studies were cross-sectional (i.e., we don’t know what leads to what) I would say that right now there is not enough convincing evidence to make any recommendations based on this work. However, based off other research that has examined the impact of loneliness and social isolation on well-being, quality of life, mental health, and physical health we know enough to know that being socially connected and feeling like we have meaningful relationships with other people are really important not just for our well-being but also for our health. For anyone who feels like they might be affected by loneliness and social isolation, there are some brilliant organisations out there that can help. In the UK we have groups like the Campaign to End Loneliness, Lonely not Alone, and Age UK to name a few, all of whom provide help and support for people young or old who might feel lonely or isolated.
JA: How can readers use what you found to help others?
KS: There is no doubt that feeling lonely is an unpleasant experience that impacts our well-being, and that being socially isolated (especially when that isolation has been forced upon you) can be a source of stress for people. I think the most important thing we can do as a society is to recognise that being socially connected and having meaningful relationships with others is important to all of us. Understanding how important social connections are can help us understand the importance of reaching out to one another. This can be as simple as picking up the phone to have a chat with someone that you haven’t spoken to in a while.
JA: What are you currently working on that you might like to share about?
KS: Alongside this paper, I am interested in questions like: Does loneliness lead to poor health or poor health to loneliness? Is it as simple as loneliness and social isolation leading directly to poor health, or is this link explained by something else? I have been working on studies that are looking at loneliness in a range of long-term conditions like stroke, cerebral palsy, and fibromyalgia. We are also doing another really interesting review (with Christina) to look at whether loneliness is linked with healthcare use in older adults. So, I am being kept very busy!
Smith K.J., Gavey S., Ridell, N.E., Kontari P., & Victor C. (2020). The association between loneliness, social isolation and inflammation: A systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews 112, 519-541.