Recognising how early experiences frame and impact later health is a key concern for DOHaD. However, rarely in DOHaD studies are the synergistic characteristics of diseases throughout the lifecourse a central focus. Syndemic theory posits that disease concentrations (where diseases cluster together) and disease interactions (what adverse effects result from the clustering) cause more health adversity due to their synergistic dynamics. In this chapter, we consider how syndemic theory can contribute meaningfully to DOHaD studies because it considers how and why diseases occur, cluster, and interact across the lifecourse and integrates a synergistic understanding of early stressors and long-term adverse health. We describe the history of the syndemic concept and discuss the synergies of syndemic and DOHaD theory. We draw on our work with the ‘Birth to Thirty’ birth cohort based at the Developmental Pathways for Health Research Unit (DPHRU) at the University of the Witwatersrand to provide some examples of how social, psychological, and biological factors cluster and drive health and disease over a lifetime.

Emergencies, incidents, disasters, and disease outbreaks (EIDD) affect children, young people, and their families in many ways, including across generations through epigenetic effects. Their mental wellbeing, life, and routines that continue beyond their injury, illness, or adversity can each be affected. Their reactions and responses can be influenced by the nature and extent of their exposure, personal characteristics, pre-existing vulnerabilities and strengths, and in particular by the family and social support that is offered. Almost all adverse childhood experiences are likely to increase in pandemics and following disasters due to natural and human-induced hazards. Psychosocial problems linked with emergencies are likely to emerge over the year following these events. Social connectedness and social scaffolding mitigate adversity, and promote wellbeing and recovery. This emphasises the importance of a co-ordinated and strategically aligned, psychosocially informed, and evidence-based governmental and system-wide response working across boundaries to support children and families in such crises.

Tuberculosis was the most devastating infectious disease of the 20th century. Spread initially in the nineteenth-century fur trade, tuberculosis rose in intensity after 1900, with its greatest impacts in the 1920s and 1930s. This chapter shows the prevalence of tuberculosis infection, its interaction with other pathogens, and the impacts of tuberculosis on children and young adults especially, including how the residential school system amplified the epidemic in the North. More than any other disease, tuberculosis changed Indigenous relationships with the land. The colonial state belatedly responded to this epidemic, relocating the sick to institutions in southern Canada. This policy of medical relocations became emblematic of Northern health history and colonialism in the decades to come.

In this chapter we look at the social inequalities of physical health in relation to the poorer physical health experienced by people with mental health conditions and their access to health services. People with mental health conditions often experience a ‘triple jeopardy’: they experience an excess of physical health problems relative to their peers in the general population, are more likely to get serious forms of physical illness, and, once diagnosed, are more likely to die within five years. They face greater difficulties accessing good-quality healthcare than people without mental health conditions. These distinct findings also give us an illustration of the complex pathways involved in the exclusionary processes, this time linking mental and physical health conditions and outcomes through a synchrony of broader structural factors, social inequalities, early life experiences, life course adversities, risky health behaviours, the nature of the mental health condition, the medications prescribed, and the discriminatory attitudes prevalent in public services and in broader society. They also point to the need to clearly appreciate the disabilities associated with mental health conditions and to develop broad public health approaches to address these inequalities in health outcomes.