Nine-year study links changing loneliness patterns to increased heart disease risk

The study analyzed data from 10,823 adults aged 45 and older who participated in the China Health and Retirement Longitudinal Study (CHARLS). Researchers examined information collected between 2011 and 2020, excluding participants who already had cardiovascular disease at the beginning of the study.

Loneliness and social isolation are not the same

Although the terms are often used interchangeably, social isolation and loneliness describe different experiences. Social isolation refers to having limited social contacts or relationships, while loneliness is the subjective feeling that one's social connections are insufficient or do not meet emotional needs.

Both have previously been linked to adverse health outcomes, including cardiovascular disease. However, examining either factor at a single point in time may overlook how the two interact and change over the years.

To investigate this relationship, researchers tracked patterns of social isolation and loneliness together and assessed how they were associated with subsequent cardiovascular risk.

Social isolation was measured using five indicators: marital status, living arrangements, contact with children, participation in social activities, and rural residence. Loneliness was assessed by asking participants how often they had felt lonely during the previous week.

Using a statistical method known as group-based dual-trajectory modeling, the researchers classified participants according to how their levels of social isolation and loneliness developed over time. They then compared cardiovascular disease risk across the resulting groups.

Fluctuating loneliness was associated with the highest risk

During the follow-up period, researchers recorded 2,589 new cases of cardiovascular disease. The analysis identified five distinct patterns of social isolation and loneliness.

The highest risk was observed among participants who had moderate social isolation but experienced fluctuating loneliness. Their risk of cardiovascular disease was 53% higher than that of the reference group, which had moderate social isolation and consistently low levels of loneliness.

In this group, loneliness initially decreased, rose substantially between 2013 and 2018, and then declined again by 2020. The findings suggest that changing feelings of loneliness may be associated with cardiovascular risk even when a person's level of social isolation is not particularly high.

Participants who experienced both high social isolation and high loneliness also had an elevated risk. Their risk of cardiovascular disease was 29% higher than that of the reference group.

An unexpected finding emerged among participants who initially reported low social isolation and low loneliness. Their cardiovascular disease risk was 16% higher than that of the reference group. Social isolation increased in this group during the later years of follow-up, and participants were more likely to smoke, consume alcohol, and have overweight or obesity.

The researchers cautioned that other health factors, unmeasured influences, and potential biases could help explain this association. The result therefore does not suggest a straightforward relationship in which greater social isolation always corresponds to greater cardiovascular risk.

Meanwhile, participants with high social isolation but low loneliness did not show a statistically significant difference in cardiovascular disease risk compared with the reference group. This finding highlights the distinction between a person's actual social circumstances and how they feel about them. However, it does not mean that social isolation is harmless or that low loneliness necessarily protects against heart disease.

The study cannot prove that loneliness causes heart disease

The findings should be interpreted with caution because the study was observational. It can identify associations but cannot establish that loneliness or social isolation directly causes cardiovascular disease, or that interventions designed to reduce loneliness would prevent heart attacks and strokes.

Other factors may influence both loneliness and cardiovascular health. It is also possible that underlying health problems contributed to loneliness or social isolation before cardiovascular disease was diagnosed, creating the possibility of reverse causation.

The study had additional limitations. Loneliness was measured using a single question, which may not fully capture the complexity of the experience. Cardiovascular outcomes were based on participants' reports of physician-diagnosed heart disease or stroke rather than independent clinical verification, potentially introducing measurement errors.

Furthermore, all participants were from China, so the findings may not apply equally to other populations. The researchers also included rural residence in their social isolation measure, an indicator that may not be directly comparable across countries and communities.

Assessing emotional well-being may help identify people at risk

The findings suggest that the relationship between social isolation, loneliness, and cardiovascular disease is more complex than the size of a person's social network alone can explain.

People experiencing persistent high levels of loneliness and those whose feelings of loneliness fluctuate substantially may represent groups worth considering in cardiovascular risk assessments. Evaluating emotional well-being alongside social circumstances could help identify middle-aged and older adults who might benefit from appropriate cardiovascular screening and social or emotional support.

However, further studies are needed to determine whether interventions that reduce loneliness or improve social connections can actually lower the risk of cardiovascular disease.