Social connection and satisfying relationships are fundamental for development, reproduction and survival. The impact of social influences on health and well-being has been extensively investigated through diverse scientific methodologies like epidemiological studies, network analyses, clinical trials and controlled experiments. Consistent evidence indicates that loneliness and social isolation negatively affect mental, physical, and cognitive health, with the most compelling findings linking these factors to an increased risk of premature mortality. 1 Several meta-analyses find that the risk of all-cause mortality is increased by 26 %. Moreover, these findings were consistent across various factors, including age, gender, cause of death, country of origin, and baseline health status 2
Existing research makes a difference in all-cause mortality and cause-specific mortality, particularly when talking about cardiovascular diseases or strokes. All-cause mortality refers to the collective risk of death from all conditions associated with loneliness, while cause-specific mortality focuses on the risk of dying from a specific condition closely linked to loneliness or social isolation.
Research has explored the individual and combined effects of loneliness and social isolation on mortality risk. While both factors independently correlate with higher mortality, studies suggest that social isolation is the stronger predictor when both are analyzed together. For example, some studies show that only social isolation remained significant after controlling for demographic, socio-economic, and health factors. 3 Beller and Wagner observed that loneliness and social isolation interact synergistically: greater social isolation amplifies the impact of loneliness on mortality, while higher loneliness intensifies the effect of social isolation. 4
The impact of social relationships on mortality risk can be compared to other well-established lifestyle risk factors like physical activity, alcohol consumption, smoking cigarettes, air pollution or obesity. 5
Physical health
In addition to their association with increased mortality risk, social isolation and loneliness are linked to various health issues, including cardiovascular diseases, stroke, functional decline, and, to some extent, reduced immune function and diabetes. 3
Cardiovascular diseases
Cardiovascular diseases include diseases affecting the heart or blood vessels like heart attacks or strokes. A meta-analysis which is based on 23 different studies shows that loneliness and social isolation are linked to a 29 % higher risk of coronary heart disease and a 32 % higher risk of stroke. These associations were observed in both genders and remained significant regardless of traditional heart disease risk factors. Studies show that loneliness is linked to an increased risk of high blood pressure, particularly among middle-aged and older adults, and inflammatory reactivity. 3
Functional and motor decline
Loneliness is linked to increased functional and motor decline, including greater difficulty with activities of daily living and reduced muscle strength, mobility, and motor performance. 6 It remains unclear whether loneliness contributes to functional decline directly or indirectly through processes like cardiovascular diseases or inflammation. 7
Diabetes and cholesterol
Few studies have linked loneliness to developing diabetes for men. A cross-sectional study in Switzerland shows that lonely people have a 40 % higher chance of developing diabetes and 31 % higher chance to have higher cholesterol levels. 8
Cognitive Health
Cognitive function encompasses a range of mental processes that enable an individual to acquire knowledge, reason, and carry out plans. These processes include perception, memory, learning, attention, decision-making, and language skills. 9
Cognitive decline
Several studies have explored the relationship between loneliness and/or social isolation, and cognitive decline, especially in older adults. Even though some studies show a link between loneliness and cognitive decline, they cannot agree on what part of the cognitive function is affected. 3
Alzheimer’s and Dementia
Most evidence suggests a correlation between loneliness and dementia, comparable to the other dementia risk factors like physical activity, low education and late-life-depression. 10 While a study from 2018 found no association between loneliness and dementia, there are other studies showing that there is a link between loneliness and developing dementia. To address the potential problem of reversed causality – where early-stage dementia leads to difficulties engaging in social interactions and therefore people feeling lonely – the study doesn’t include people in those early stages. 3
Mental health
A wide range of literature shows a significant relationship between loneliness and mental health issues like depression and anxiety as well as suicide and suicidal ideations. 3
Depression and Anxiety
Lonely individuals tend to experience more depressive symptoms and report being less happy, less satisfied, and more pessimistic. Additionally, loneliness and depression share common features, such as feelings of helplessness and emotional pain. 11 Another study also shows an association between poor social connection and social anxiety in both adolescents and adults. 1
Suicide and Suicidal Ideation
Studies indicate a connection between loneliness and suicide. A study of individuals who have attempted suicide found that loneliness is frequently cited as a contributing factor. 12
Taking loneliness seriously
Research shows that loneliness affects health, but the relationship is also bidirectional – some health conditions such as poor physical health, disabilities, or hearing loss, can also increase the likelihood of loneliness. The reported evidence highlights that loneliness should be taken more seriously as a risk factor for various health problems. 3
Sources
[1] J. Holt-Lunstad und Department of Psychology, Brigham Young University, Provo, Utah, USA, „Social Connection as a Public Health Issue: The Evidence and a Systemic Framework for Prioritizing the “Social” in Social Determinants of Health“, 2022. [Online]. Verfügbar unter: https://doi.org/10.1146/annurev-publhealth-052020-110732
[2] J. Holt-Lunstad, T. B. Smith, M. Baker, T. Harris, and D. Stephenson, “Loneliness and social isolation as risk factors for mortality: A meta-analytic review,” *Perspect. Psychol. Sci.*, vol. 10, no. 2, pp. 227–237, Mar. 2015, doi: 10.1177/1745691614568352. PMID: 25910392.
[3] J. Baarck, M. Kovacic und Joint Research Centre (JRC), „The Relationship between Loneliness and Health“, Publications Office of the European Union, literature review, 2022. doi: 10.2760/90915.
[4] J. Beller and A. Wagner, “Loneliness, social isolation, their synergistic interaction, and mortality,” Health Psychol., vol. 37, no. 9, pp. 808–813, Sep. 2018, doi: 10.1037/hea0000605. PMID: 30138019.
[5] J. Holt-Lunstad, T. F. Robles und D. A. Sbarra, „Advancing social connection as a public health priority in the United States.“, American Psychologist, Bd. 72, Nr. 6, S. 517–530, Sep. 2017, doi: 10.1037/amp0000103.
[6] K. Beaton and K. Grimmer, “Tools that assess functional decline: systematic literature review update,” Clin. Interv. Aging, vol. 8, pp. 485–494, 2013. Available at: https://doi.org/10.2147/CIA.S42528.
[7] A. S. Buchman et al., “Loneliness and the rate of motor decline in old age: the Rush Memory and Aging Project, a community-based cohort study,” BMC Geriatr., vol. 10, no. 1, p. 77, 2010. Available at: https://doi.org/10.1186/1471-2318-10-77.
[8] R. A. Richard, S. Rohrmann, C. L. Vandeleur, M. Schmid, J. Barth, and M. Eichholzer, “Loneliness is adversely associated with physical and mental health and lifestyle factors: Results from a Swiss national survey,” PLoS One, vol. 12, no. 7, p. e0181442, Jul. 2017, doi: 10.1371/journal.pone.0181442. PMID: 28715478; PMCID: PMC5513556.
[9] K. Kiely, “Cognitive function,” in Encyclopedia of Quality of Life and Well-Being Research, A. C. Michalos, Ed., Dordrecht: Springer Netherlands, 2014, pp. 483–484. Available at: https://doi.org/10.1007/978-94-007-0753-5_2939.
[10] J. S. Kuiper, M. Zuidersma, R. C. Oude Voshaar, S. U. Zuidema, E. R. van den Heuvel, R. P. Stolk, and N. Smidt, “Social relationships and risk of dementia: A systematic review and meta-analysis of longitudinal cohort studies,” Ageing Res. Rev., vol. 22, pp. 39–57, Jul. 2015, doi: 10.1016/j.arr.2015.04.006. PMID: 25956016.
[11] R. Mushtaq, S. Shoib, T. Shah und S. Mushtaq, „Relationship Between Loneliness, Psychiatric Disorders and Physical Health ? A Review on the Psychological Aspects of Loneliness“, JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH, Jan. 2014, doi: 10.7860/jcdr/2014/10077.4828.
[12] L. M. Heinrich, E. Gullone und School of Psychology, Psychiatry, and Psychological Medicine, Faculty of Medicine, Nursing, and Health Sciences, Monash University, VIC 3800, Australia, „The clinical significance of loneliness: A literature review“, 2006. [Online]. Verfügbar unter: https://doi.org/10.1016/j.cpr.2006.04.002