Loneliness and social isolation as risk factors for CVD
A recent meta-analysis has shown that loneliness and social isolation are risk factors
for coronary heart disease and stroke.1 These latest findings, specific to cardiovascular
outcomes, are consistent with substantial research indicating broad health risks (eg,
immune functioning, cardiovascular functioning, cognitive decline) associated with
the quantity and quality of social relationships—including several meta-analyses documenting
mortality risk.2
3 In the most comprehensive of these,3 the overall odds for mortality was 1.50, similar
to the risk from light smoking and exceeding the risks conferred by hypertension and
obesity. Thus, the epidemiological data suggest that having more and better quality
social relationships is linked to decreased health risks and having fewer and poorer
quality relationships increased risk.2
3
Research has also documented the influence of social connections (including measures
specific to loneliness and isolation) on multiple pathways involved in both the development
and progression of coronary heart disease and stroke. As depicted in figure 1, these
include lifestyle (eg, nutrition, physical activity, sleep),4 treatment adherence
and cooperation,5 and direct effects on surrogate biological markers.6
7 Recent longitudinal data from four nationally representative US samples revealed
a dose–response effect of social integration on several surrogate biomarkers of cardiovascular
disease including hypertension, body mass index, waist circumference and inflammation
(hs-CRP).6 Moreover, most epidemiological studies control for lifestyle factors (eg,
smoking, physical activity), documenting an independent influence of social relationships
on mortality. Taken together, these latest findings specific to loneliness and isolation1
bolster the already robust evidence documenting that social connections significantly
predict morbidity and mortality, supporting the case for inclusion as a risk factor
for cardiovascular disease (CVD).
Figure 1
Simplified model of possible direct and indirect pathways by which social connections
influence disease morbidity and mortality.
Targeting social isolation and loneliness in evidence-based patient care
How should these data inform clinical practice? To begin, the data suggest the need
for greater prioritisation and inclusion of social variables (quantity and quality)
in medical education, individual risk assessment and public health surveillance, guidelines
and policies applied to populations and health service delivery.
Medical education
The cumulative evidence points to the benefit of including social factors in medical
training and continuing education for healthcare professionals. Physicians supervising
students and residents’ can assess patients’ social risk factors and then discuss
with patients the importance of nurturing and maintaining positive social connections
as part of a healthy lifestyle. Evidence-based training could include social factors
in medical case examples and textbooks to provide realistic patient descriptions with
life circumstances relevant to disease development, progression and response to treatment.
For instance, a case description of a 55-year-old male with hypertension and atrial
fibrillation who is responding poorly to treatment could include relevant circumstances
of intense marital conflict that have elevated levels of distress and increased adiposity
due to increased consumption of low quality foods away from home. Given the multiple
social factors associated with health conditions and patients’ responses to treatment,
medical training that requires consideration of patients’ social circumstances could
improve patients’ outcomes.
Medical training can also make explicit the processes for making effective referrals
to mental health and social support services. In the hypothetical case of the patient
mentioned above, referral for marital counselling and stress management therapy would
be indicated. Medical training can encourage physicians to proactively identify relevant
social and psychological conditions, rather than ignore those conditions simply because
they would be treated by another specialist. In the same way cardiologists refer and
follow-up with patients who have comorbid renal disease, they should refer and follow-up
with patients experiencing social isolation or distress. Social factors must now be
given attention in coursework detailing the major findings of health psychology and
neuroscience, rather than relegating such information to a side note (eg, a mini-lecture
during students’ exposure to psychiatry).
Risk assessment
Patient information should be used to inform treatment. Hospitals and clinics should
include assessments of social integration and/or loneliness in electronic medical
records. This important step can identify individuals at risk—which may also have
multiple implications for health service delivery. Further, at a broader level, population-wide
surveillance will aid public health efforts.
Such efforts will require multifactorial risk assessment. While short and simple assessments
are desirable, single-item assessments would be insufficient and problematic. According
to meta-analytic data,3 multivariate measures of social relationships yield data much
more predictive of death (OR=1.91) than simplistic measures (OR=1.19). Further, although
loneliness and social isolation entail equivalent levels of risk, they are not interchangeable.
Social isolation denotes few social connections or interactions, whereas loneliness
involves the subjective perception of isolation—the discrepancy between one's desired
and actual level of social connection. Although social isolation and loneliness may
co-occur, individuals can be isolated without feeling lonely or feel lonely despite
having others present. Thus assessments should include objective/quantitative aspects
of relationships (eg, network size, marital status), as well as more subjective/qualitative
aspects (eg, loneliness, social support, perceived relationship quality). Each significantly
predicts risk for mortality,3 and may potential tap into different mechanistic pathways;
thus, multifactorial assessments may best capture overall risk. A key challenge will
be how to develop a point-of-care assessment that is multifaceted, has predictive
validity, and easily incorporated into day-to-day clinical practice.
Population-based recommendations and policies
The WHO now lists ‘Social Support Networks’ as a determinant of health (http://www.who.int/hia/evidence/doh/en/).
Major health organisations specific to cardiovascular disease (eg, American Heart
Association, British Heart Foundation) should also include social connections in their
lists of major risk factors, similar to comparable lifestyle factors that currently
receive sustained attention. Government and professional health organisations will
need to establish recommendations for social relationship quantity and quality for
the broader population and specific risk groups. These recommendations should be based
on empirical evidence, subject to periodic revision and annual public health surveillance.
Among other European nations, the UK has already undertaken several public health
initiatives intended to reduce social isolation and decrease risk for premature mortality.
Current efforts are focused primarily on older adults or individuals reporting high
levels of loneliness; however, recommendations and cautions can be broadly applied.
A broad approach is supported by evidence indicating (a) remarkable consistency of
effect across different countries and across multiple individual characteristics (eg,
gender, health status), with data suggesting greater relative risk prior to retirement
age;2 (b) a gradient effect of social connection rather than a threshold effect3
6 and (c) social relationships affect cardiovascular health by altering biomarkers
and shaping health behaviours across the lifespan—including adolescence, young adulthood,
middle age and old age.6 Thus, efforts to promote public health via social connection
need not be limited to specific groups but can be applied across the risk trajectory.
Health service delivery: prevention
Attention to social connection needs to be incorporated into existing preventative
efforts. Chronic illnesses, including cardiovascular diseases, develop slowly over
decades. Because social relations influence multiple mechanistic pathways in both
the development and progression of disease, they warrant attention in primary, secondary
and tertiary prevention efforts. Given efforts aimed at primary prevention result
in lower economic costs to the individual, family, employers and the broader healthcare
system—we urge healthcare and health policy professionals to prioritise social connections
in prevention efforts.
Further scientific inquiry
Despite robust literature of epidemiological evidence, several important questions
remain.
Causal mechanisms
Social isolation and loneliness are clearly risk factors for cardiovascular disease
(CVD).8 However, the term risk factor can imply prediction and causality, and causality
is not easily established. Similar to other risk factors for CVD (eg, hypertension,
obesity, smoking, cholesterol levels) the influence of social relationships is complex
and multifactorial (no single putative mechanism).8 Furthermore, we must take a multilevel
approach considering microlevel (eg, genetic markers of susceptibility, gene–environment
interactions) to macrolevel (eg, cultural norms, neighbourhood characteristics) processes
to better understand additional pathways by which social relationships influence physical
health, as well as the pathways by which we may intervene to reduce risk and improve
health.
Interventions
Perhaps the biggest challenge and opportunity for the future is to design effective
interventions to increase social connections. Previous interventions involving social
support have had mixed results. Additional research is needed to determine what works
best for whom, in what conditions. Notably, the major effects established via epidemiological
data are based on existing social relationships (eg, family, friends), yet many clinical
interventions use hired personnel to deliver support to patients. This discrepancy
may be problematic because support from the patients’ family and broader social networks
may differ from that provided by hired personnel in several important ways (eg, trust
built over decades, regular social contact, importance of the relationship, degree
of social control, sense of obligation in the relationship). Thus, efforts to strengthen
existing family relationships may prove more effective than interventions by hired
personnel.
On a related note, policies that for essential reasons restrict access to patients’
medical records and information may have indirectly contributed to a practice climate
not conducive to family involvement, even when the patient authorises family involvement.
Hospitals and clinics should make efforts to enhance family involvement when authorised
by the patient.
Social technology
Social technology has rapidly become a dominant form of communication and social interaction.
While existing and developing technology has the potential to combat loneliness and
isolation (facilitating social connection), it may also contribute to problems exacerbating
risk. With such rapid changes in the way people are interacting socially, empirical
research is needed to address several important questions. Does interacting socially
via technology reduce or replace face-to-face social interaction and/or alter social
skills? Due to the rapid and instant access afforded, does technology accelerate relationship
processes (both positive and negative) leading to accentuation of sociality or lack
thereof? Do social relationships/interactions via technology have a similar influence
health and well-being?
Conclusions
Decades of research have documented an unequivocal influence of social connections
on longevity,2
3 with a recent meta-analysis confirming the association between social isolation
and CVD.1 Given projected increases in levels of social isolation and loneliness in
Europe and North America, medical science needs to squarely address the ramifications
for physical health. Similar to how cardiologists and other healthcare professionals
have taken strong public stances regarding other factors exacerbating CVD (eg, smoking,
diets high in saturated fats), further attention to social connections is needed in
research and public health surveillance, prevention and intervention efforts. Those
efforts will necessarily integrate methods and findings from related disciplines and
expand the complexity of research questions and analyses.