The ‘loneliness’ epidemic: a new social determinant of health?
Introduction
In May 2023, the US Surgeon General declared ‘loneliness’ as a new epidemic,1 and in November 2023, the World Health Organization (WHO) launched an International Commission to look into loneliness as a pressing global health threat.2 The rising prevalence of loneliness is indeed a major cause of concern, as many studies over the past 2 decades have shown that loneliness is associated with mortality outcomes, related to underlying biological processes, unhealthy/maladaptive behaviours and increased rate of physical and mental health conditions.1 However, unlike many other conventional social determinants of health, loneliness is a prevalent phenomenon that affects people of all age groups and socioeconomic backgrounds.1 In the recent COVID-19 pandemic, with the imposed lockdowns, social-distancing measures and the drastic shift of educational, work and leisure activities from physical to virtual platforms, the problem of social isolation has now well and truly emerged at the forefront of public health awareness.1
But why is this problem important to clinicians? I suggest that, while the modern clinician is still required to be competent in diagnosing and treating disease, there has now been a greater professional responsibility to recognise and tackle social determinants of health as part of a broader, preventative and population health strategy.3 Moreover, it is also found that our conventional methods of preaching behavioural modifications to patients are not actually as effective as implementing broader healthcare and societal interventions that create a more conducive ecosystem to support healthy behaviours.3
Therefore, in this article, I hope to draw the attention of the medical community to the present loneliness epidemic, by reviewing its conceptualisations, underlying contributors and clinical implications. In addition, I highlight practical, multilevel healthcare strategies that can be adopted to address this major public health concern.
What is loneliness and why is it important?
Loneliness is defined as a psychologically distressing perception of social isolation, which occurs when there is a mismatch between one's desired amount and quality of social interactions and relationships and the actual experience.1, 4 In 1973, Weiss described the multidimensional aspect of loneliness – where ‘social’ isolation pertains to a lack of social network (e.g. family, friends and colleagues), whereas ‘emotional’ isolation refers to the absence of quality interactions or intimate relationships.5
In recent years, loneliness has become highly prevalent. In the United States, one in two adults reported experiencing loneliness,1 and in European studies, the prevalence of loneliness was 2.9%, 2.7% and 5.2% in young, middle-aged and older adults respectively in northern Europe, and 7.5%, 9.6% and 21.3% in young, middle-aged and older adults respectively in eastern Europe.6
From the literature, the known predictors of loneliness generally include ill health, being single, older adults who stay alone and have infrequent social interactions, those with psychiatric disorders, patients with chronic health conditions that limit communication/mobility and stigmatised groups in society.7, 8 However, the recent exponential rise in digital and social media consumption has further changed the way people connect with one another, leading to increasingly superficial and inauthentic social relationships.1
Clinical and health implications of loneliness
It is found that loneliness, in terms of actual and perceived social isolation, is associated with an approximately 30% higher risk of early mortality.4 To put this in a public health perspective, the mortality impact of loneliness is actually similar to smoking up to 15 cigarettes per day.9
This observation can be attributed to several reasons. First, social isolation is associated with innate biological/physiological changes, such as poorer immunity, heightened stress and inflammatory response, suboptimal physiological repair activity and impaired metabolism.10 Intriguingly, a previous study on college freshmen found that loneliness was associated with poorer immunisation response to the influenza vaccine, which may be related to stress-related physiological changes.11 Second, loneliness is associated with unhealthy/maladaptive behaviours such as smoking, substance use, physical inactivity, poor dietary habits and lack of sleep.4, 12 Third, loneliness/social isolation is directly associated with various physical and mental health conditions, including metabolic syndrome,13 cardiovascular diseases such as ischaemic heart disease and stroke,14 cognitive impairment15 and functional decline in older adults,16 as well as psychiatric illnesses such as depression, anxiety and suicidal ideation.17 In 2023, an American Cancer Society cohort study found that cancer survivors with elevated perceptions of loneliness had significantly increased mortality risk.18
In terms of healthcare resources and financing, loneliness/social isolation is associated with increased health-seeking behaviours,19 hospital admissions20 and overall healthcare costs.21 In the United States, social isolation in older adults reportedly accounted for AU$6.7 billion in excess annual Medicare spending,21 and in Australia, adverse health outcomes related to loneliness contributed to up to AU$2.7 billion in healthcare costs.22
Multilevel healthcare strategies to address the loneliness epidemic
First, at the individual level, there needs to be greater awareness of loneliness as fundamentally a health problem, willingness to identify underlying predispositions and amenability to interventions to address it. To improve public awareness of loneliness/social isolation as a risk factor of ill health, similar health campaign strategies through mass/social media and healthcare platforms used to regulate other health behaviours such as smoking and dietary habits can be adopted. Given that loneliness is fundamentally a psychological perception that can exist in different dimensions, individuals must be willing to honestly reflect on the underlying predisposing factors for this phenomenon – be it a quantitative lack of social contact, inauthenticity of current relationships, inadequate support for personal needs, lack of social participation or sense of belonging to a community or maladaptive perception of personal relationships.
Second, at the healthcare level, clinical screening tools can be adopted to detect loneliness in at-risk patients. Validated screening modalities for loneliness include the revised UCLA Loneliness Scale (1980)23 and the Three-Item Loneliness Scale (2004).24 However, clinical criteria that include predictors of social isolation need to be established in order to identify at-risk patients who would benefit from screening. This is not dissimilar to how we screen patients in acute or primary care who might benefit from mental health, cognitive, nutrition or frailty assessments, in order to introduce timely clinical interventions. To this end, there have been several ‘loneliness-reduction’ interventions described in the literature that can be provided in healthcare settings, including cognitive-behavioural/psychotherapy, animal therapy, music therapy, counselling and technological interventions, albeit with varying efficacies.25 Moreover, both referral-based (physician-initiated referral to social coordinators/community workers) and nonreferral-based (external organisations recruiting suitable patients) pathways can be incorporated into standard primary and ambulatory care workflow, so that patients identified to be experiencing loneliness can be provided with suitable social interventions.26
Finally, at the societal/population level, loneliness-reduction interventions can be classified into four main strategies: (i) social skills training (e.g. verbal/nonverbal communication techniques, giving and receiving of compliments, enhancing attractiveness and family therapy programmes), (ii) enhancing social support (e.g. peer support groups, recreational groups, bereavement programmes and elder support initiatives), (iii) increasing opportunities for social interaction (e.g. shared living spaces and community programmes), and tackling maladaptive social cognition (reframing and replacing negative thoughts with more constructive ones).27, 28
