Chronic loneliness associated with higher stroke risk independent of depressive symptoms or social isolation

In a recent study published in eClinicalMedicine, researchers determined the relationship between loneliness and incident stroke risk in the United States.

Background

Stroke is a major worldwide health problem, particularly among elders. Hypertension, diabetes, and smoking are associated with a lower risk of stroke. Loneliness, a potential risk factor, might be modifiable in the elderly population and a target for stroke prevention. However, few studies have evaluated the links between loneliness and stroke, including depressive symptoms.

Loneliness, regardless of social isolation or depressive symptoms, appears to be connected with various cardiovascular health outcomes. There is limited data on whether changes in loneliness over time are associated with stroke risk in middle-aged and older individuals.

About the study

In the present study, researchers investigated whether loneliness chronicity can increase stroke incidence among United States adults.

The researchers evaluated Health and Retirement Study (HRS) data from 2006 to 2018. For baseline loneliness studies, they included only United States residents aged ≥50 years, eliminating those with insufficient data or who died at baseline. They analyzed changes in loneliness over two periods (baseline or T1 in 2006 or 2008 and T2 in 2010 or 2012), including individuals aged ≥50 years at study initiation without stroke in the exposure assessment period.

The researchers assessed loneliness using the three-component updated University of California, Los Angeles (UCLA) Loneliness Scale. They calculated loneliness scores, dichotomized aloneness measures, and explored loneliness patterns during the study period. They developed a social isolation measure based on the Berkman-Syme Social Network Index (SNI) to assess social isolation across domains such as volunteer engagement, marital status, and interaction with neighbors and children. They excluded individuals who did not complete loneliness scale tests or died at the time of exposure assessment.

The researchers used Cox proportional hazards regression models to calculate the hazard ratios (HR) for the associations between baseline aloneness (12,161 individuals) and stroke incidence over 10 to 12 years, loneliness patterns (8,936 individuals), and new-onset stroke over the next six to eight years, controlling for demographic characteristics, health conditions, and health behavior.

Study covariates included age, gender, race, ethnicity, educational attainment, income, physical activity, body mass index (BMI), smoking status, alcohol consumption, and medical problems such as angina, hypertension, coronary artery disease, heart attack, congestive cardiac failure, and diabetes. The researchers conducted sensitivity analyses by determining the relationship between loneliness and stroke incidence regardless of social isolation and depressive symptoms, utilizing lower loneliness score thresholds and inverse probability weighting.

Results and discussion

Using baseline aloneness (N = 12,161) ratings, the researchers discovered 1,237 occurrences of incident strokes throughout a 10- to 12-year follow-up period (2006–2018). During six to eight follow-up years (2010–2018), they detected 601 stroke incidence cases among 8936 people who experienced loneliness. The average participant age at baseline was 67 years; the majority were female (61%), non-Hispanic Whites (80%), and had constantly low aloneness scores (85%) across time.

Individuals with consistently high loneliness were younger (65 years vs. 68 years), had lower than high school-level education (26% vs. 18%), showed a lower likelihood of engaging in strenuous physical exercise (73% vs. 54%), and an increased likelihood of having a medical condition. Aloneness at T1 had a minimal correlation with social isolation and depressive symptoms but a significant correlation with aloneness at T2.

Higher baseline loneliness scores were related to increased stroke risk for continuous (HR, 1.1) and dichotomized-type (HR, 1.3) loneliness measures, with persistent associations after adjusting for social separation but not for depression symptoms. Individuals with continuously high patterns of loneliness (versus continuously low) had a significantly higher risk of stroke incidence (HR, 1.6) despite correcting for social isolation and depressive symptoms. Sensitivity analyses yielded similar findings.

Loneliness can raise the risk of stroke through physiological, behavioral, and psychological processes. Physiological mechanisms include high blood pressure, increased exercise, and weakened immunity. Unhealthy habits such as poor medication adherence, smoking, alcohol consumption, and sleep quality are all examples of behavioral processes.

Depression, anxiety, and social isolation are examples of psychosocial processes. Chronic loneliness may suggest an inability to create fulfilling social interactions, resulting in interpersonal issues. Unobserved social actions, such as neuroticism or personality traits, might potentially heighten the risk of stroke.

Conclusion

The study found that persistent loneliness is associated with an increased risk of stroke, regardless of social isolation or depressive symptoms. Each unit increase in loneliness score increased stroke risk by five percent. Loneliness was associated with a 25% increase in the risk of stroke.

Addressing loneliness is critical for stroke prevention, and repeat tests can help identify people who are at risk. Future studies should evaluate the long-term associations, processes, and efficacy of loneliness therapies and the impacts of longer-term changes in loneliness status.