This Series paper investigates syndemics involving non-communicable diseases (NCDs) to show the complexities through which social, psychological, and biological factors come together to shape emergent and pervasive global health problems. Syndemic refers to the clustering of two or more diseases within a population that contributes to, and results from, persistent social and economic inequalities.1 The concept focuses on instances in which multiple health problems interact, often biologically, with each other and the sociocultural, economic, and physical environment.1, 2 For example, in the mid-1990s, the anthropologist Merrill Singer2, 3, 4, 5, 6 explored how substance abuse, violence, and AIDS cluster together and affect one another among an impoverished inner-city population in the USA; he coined the term SAVA syndemic to describe this process. By recognising how these mutually interacting factors promote adverse health outcomes, the syndemic framework moves beyond disease-specific or multimorbidity models to evaluate how social and economic conditions foster and exacerbate disease clusters.7, 8 Syndemics provide a tool for empirically evaluating how health statuses of multi-morbidity arise in a population, and what health interventions might be most effective for mitigating them.
We focus on type 2 diabetes and discuss how mental illness and infectious disease can cluster with metabolic conditions in both high-income countries (HICs) and low-income and middle-income countries (LMICs). As obesity and other NCDs such as diabetes, hypertension, and heart disease escalate in LMICs, these conditions become more prevalent among low-income populations, shifting from the affluent to the less affluent.9 Although there are recognised global transformations in obesity, food practices, and activity patterns,10 this does not ensure that universal one-size-fits-all interventions will be effective across populations. We argue that contextual factors matter, because people experience diabetes differently across social contexts, and this affects how diabetes becomes syndemic. This framework is exemplified in scholarship on syndemic suffering that has employed empirical analysis of individual-level experiences of syndemic interaction to show how social problems that cluster with diabetes and depression differ across contexts.7, 11, 12 For instance, immigration-related stress is central to the mental health of many Mexican immigrant women with diabetes who have undocumented family members or are themselves undocumented.7 This mental stress differs from women residing in the same communities with different ethnic and legal statuses, such as Puerto Ricans and African Americans.8 A syndemic approach can then be applied to design integrated chronic care that can be locally relevant and most effective at mitigating the root causes of co-occurring conditions in public health and medicine.13
Key messages
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Non-communicable diseases share common risk factors resulting in escalation of comorbidities, especially among low-income, marginalised populations worldwide
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The clustering of social and health problems is often overlooked in social epidemiology and other models of epidemiological transition
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Syndemic care requires that we recognise how social problems cluster with and affect medical problems, and that co-occurring diseases can present differently than singular disorders
Our goal is to examine how syndemic approaches previously limited to socially and economically disadvantaged populations in HICs could be expanded to apply to conditions in LMICs. We triangulate research from medicine, public health, and anthropology to illustrate how poverty, depression, and diabetes cluster in the low-income populations in HICs, and we illuminate the various facets of their interaction. We bring this discussion to LMIC contexts and discuss diabetes comorbidity with HIV in Kenya, tuberculosis in India, and depression in South Africa. Considering how social and health problems cluster together and mutually exacerbate one another differently across contexts is an indispensable way in which we can frame, understand, and treat NCDs. Through a syndemic orientation, global health practitioners can recognise in their clinical practice and community-based intervention how social, cultural, and political factors facilitate disease clusters and escalate morbidity and mortality.