Living alone for several years and/or experiencing serial relationship break-ups are strongly linked to rising levels of inflammatory markers in the blood in only men.
Although the inflammatory markers were classified as low grade, it was persistent and most likely indicated a heightened risk of age-related ill health and death, suggested the researchers.
The large population study was published online in the Journal of Epidemiology & Community Health.
The impact of relationship break-ups
Previous studies have found that divorce and committed relationship break-ups, which are often followed by a lengthy period of living alone, have been associated with a heightened risk of poor physical and mental health, lowered immunity, and death. But the studies mainly focussed on the impact of one partnership dissolution and then usually only on marital break-ups.
Therefore, the researchers wanted to uncover what impact an accumulated number of partnership break-ups or years lived alone might have on the immune system response in middle-aged individuals and whether gender and education attainment might be influential.
The study drew on information submitted to the Copenhagen Aging and Midlife Biobank (CAMB) study by 4835 participants, all of whom were aged between 48 and 62.
Information on serial partnership break-ups, which included 83 deaths of the partner, was supplied by 4612 (3170 men and 1442 women); and information on the number of years lived alone was supplied by 4835 (3336 men and 1499 women) for the period 1986 to 2011.
Years lived alone were categorised as: under one year, defined by the reference group as normal, two to six years, and seven or more years.
The researchers also obtained information on potentially influential factors:
- educational attainment,
- early major life events (loss of a parent, financial worries, family conflict, foster care),
- weight (BMI),
- long term conditions,
- medicines likely to affect inflammation (statins, steroids, non-steroidal anti-inflammatory drugs, immunosuppressants),
- recent bouts of inflammation,
- personality trait scores (neuroticism, agreeableness, and conscientiousness).
Inflammatory markers measured in blood samples
The inflammatory markers interleukin 6 (IL-6) and C-reactive protein (CRP) were measured in blood samples.
The researchers found that around half the participants had experienced a partnership break-up, and a percentage had lived alone for more than one year (54% of women, 49% of men).
Around one in five had ten or fewer years of education, and around six out of ten had one or more long term conditions. Around half had experienced early major life events, and half of the women and almost two-thirds of the men were overweight or obese.
Amongst men, the highest levels of inflammatory markers were found in those who had experienced the most partnership break-ups. They had 17% higher levels of inflammatory markers than those in the reference group. Similarly, levels of inflammatory markers were up to 12% higher in the group who had spent the most years living alone (seven or more). The highest levels of both inflammatory markers for years lived alone were observed amongst men with high educational attainment and two–six years living alone (CRP), and seven or more years spent alone (IL-6).
But these findings were observed only amongst the men, with no such associations found amongst the women.
Men tend to externalise their behaviour following a partnership break-up by drinking, for example, whereas women tend to internalise, manifest depressive symptoms, which may influence inflammatory levels differently, noted the researchers.
The study also only included a relatively small number of women (1499), which might also explain the discrepancy, they added.
This is an observational study, and as such, cannot establish cause. The researchers acknowledged that as the average age of the participants was 54, when the full consequences of exposure to inflammatory chemicals may not yet have peaked. Men also generate stronger inflammatory responses than women of the same age, they pointed out. But immune system competence tends to tail off with age, often leading to systemic low-grade inflammation, which is thought to have a key role in several age-related diseases, such as cancer, cardiovascular disease, and type 2 diabetes, they explained.
“Small numbers of break-ups or years lived alone is not in itself a risk of poor health, but the combination of (many) years lived alone, and several break-ups are in our study shown to affect both CRP and IL-6 levels significantly,” wrote the researchers.
“The levels of inflammation in our study are low, but they are also significant, clinically relevant, and most likely a risk factor for increased mortality,” they point out, adding that there are “notable numbers of people living with low-level inflammation.”
They continued: “Since the number of one-person households has been increasing throughout the past 50–60 years in most high-income countries, this group of people going through relationship break-ups, or who are living on their own for different reasons, are part of at-risk groups.”