What are the effects of loneliness on health?

Loneliness is a subjective feeling associated with a lack of social interactions in combination with several internal factors related to personality. Increasingly, loneliness is seen as a risk factor for several major negative health effects.

Solitude

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Social isolation and loneliness are both sources of chronic stress and hypervigilance that lead to reduced sleep quality, physiological changes in cardiovascular health, impaired immune function, neuroendocrine effects, and neuroendocrine effects. high levels of cortisol.

Along with poor physiological health, loneliness is associated with cognitive decline, depression, and premature mortality.

What is loneliness?

Although loneliness, combined with social isolation, has been associated with poor health, it is difficult to determine causation because the studies are observational. Biological pathways have been suggested to explain the effect of loneliness on the body.

These include levels of protective hormones that lead to adverse effects on the cardiovascular system, downregulation of the immune system, and deregulation of the neuroendocrine system due to lack or poor quality of sleep.

Additionally, loneliness increases the likelihood of individuals engaging in unhealthy behaviors such as heavy drinking, overeating, smoking, and occasional sexual activity as a form of psychological relief. Loneliness is a subjective emotion that results from social isolation, or due to a lack of trust and connection with those around them.

Loneliness, inflammation and stress

Loneliness has been associated with biomarkers of inflammation (interleukin-6, fibrinogen, and C reactive protein). Chronic inflammation is implicated in the development of cardiovascular disease and other chronic conditions associated with premature mortality.

In addition to hormonal effects, psychological stresses can trigger the autonomic nervous system and hypothalamic-pituitary-adrenal (HPA) access, and chronic activation of these systems can exert wear-and-tear effects on the cardiovascular, immune and metabolic systems. .

Although loneliness is associated with systemic inflammation and a wear and tear effect on the nervous system, the direction of causation has not been determined.

Loneliness as a risk factor for mortality

Loneliness dramatically increases the risk of premature death from all causes and is thought to rival the risk of smoking, obesity and being sedentary. The overall probability of mortality from loneliness is 1.5, which is comparable to light smoking (15 cigarettes / day) exceeding the risks posed by obesity on the type of attention.

These figures were derived from an analysis of 148 studies involving 300 and 8,849 people over 7.5 years and showed that the effect of loneliness was independent of other risk factors.

Loneliness as a cardiovascular risk factor

A recent systematic review followed by a meta-analysis of 16 regional longitudinal studies showed that the risk of coronary heart disease is approximately 29% and stroke is 32%.

This association is comparable to anxiety and stress at work which are also considered to be risk factors for the development of coronary heart disease. This finding corroborates a body of existing evidence that shows that loneliness is predictive of low morbidity and mortality.

With regard to other cardiovascular conditions, loneliness has been shown to increase systolic blood pressure; this effect may be harmful in the elderly when arterial stiffness increases with age. This is called total peripheral resistance and is the leading cause of systolic hypertension in individuals up to 40 years of age.

An increase in blood pressure can lead to premature arterial stiffening and further increase the risk of an increase in systemic blood pressure. As a result, solitary individuals can develop structural changes in the arteries that promote collagen deposition and decreased elasticity of the vessels.

Molecular Pathways Affected by Loneliness

Several mechanisms of loneliness associated with cardiovascular disease have been proposed. Loneliness activates HPA access and the sympathetic nervous system. This subsequently leads to a change in behavior that includes physical inactivity and sleep deprivation.

Activation of the sympathetic nervous system enhances a process called monocytopenia in the bone marrow that causes pro-inflammatory white blood cells to expand. The sympathetic nervous system also stimulates the movement of monocytes in the spleen.

Over time, social stress can lead to resistance to glucocorticoids, regulation of pro-inflammatory gene expression, and increased production of cytokines by immune cells. Glucocorticoids are hormones that regulate several physiological functions. They are involved in the suppression of inflammatory, allergic and immune disorders as well as in the modification of blood sugar and lipolysis.

These effects serve to modulate immune function to prevent overreaction and damage to tissues under stress. Glucocorticoid resistance subsequently leads to inflammation, muscle atrophy, central adiposity, fatty liver, osteoporosis, insulin resistance, hypertension, depression and insomnia.

Cytokines can also exacerbate resistance to glucocorticoids. This resulting increase in inflammation and oxidative stress may be involved in the development of atherosclerotic plaques and increased blood pressure.

The release of epinephrine and norepinephrine from the brain and adrenal gland can also induce vasoconstriction which is also enhanced by resistance to glucocorticoids. In addition, glucocorticoid resistance may also reduce the expression of endothelial nitric oxide synthase, resulting in decreased production of nitric oxide. This subsequently alters the vasodilation.

This further contributes to the increase in blood pressure. Although these pathways are involved in physiological changes in the body, the causal role of these mechanisms has not been demonstrated.

Understanding the association and causal pathways between loneliness and poor health is necessary in order to develop strategies and interventions to address loneliness.

The references:

  • Malcolm M, Frost H, Cowie J. Causal association of loneliness and social isolation with health-related lifestyle risk in older adults: a systematic review and meta-analysis protocol. Rev. 2019; 8 (1): 48. doi: 10.1186 / s13643-019-0968-x.
  • Xia N, Li H. Loneliness, social isolation, and heart health. Redox antioxidant signal. 2018; 28 (9): 837-851. doi: 10.1089 / ars.2017.7312
  • Steptoe A, et al. Social isolation, loneliness and all-cause mortality among older men and women. Proc Natl Acad Sci United States. 2013; 110 (15): 5797-801. doi: 10.1073 / pnas.1219686110.
  • Leigh-Hunt N, et al. An overview of systematic reviews on the public health consequences of social isolation and loneliness. Public health. 2017; 152: 157-171. doi: 10.1016 / j.puhe.2017.07.035.
  • Barnes TL, et al. Cumulative effect of loneliness and social isolation on health outcomes in the elderly. Aging Mental health. 2021: 1-8. doi: 10.1080 / 13607863.2021.1940096.
  • Valtorta NK, et al. Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies. Heart. 2016; 102 (13): 1009-1016. doi: 10.1136 / heartjnl-2015-308790.
  • Heinrich LM, Gullone E. The clinical significance of loneliness: a review of the literature. Clin Psychol Rév. 2006; 26 (6): 695-718.

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