Are There Global Syndemics?

Testing syndemic models along pathways to psychotic spectrum disorder: implications for population-level preventive interventions

BACKGROUND

Population-level preventive interventions are urgently needed and may be effective for psychosis due to social determinants. We tested three syndemic models along pathways from childhood adversity (CA) to psychotic spectrum disorder (PSD) and their implications for prevention.

METHODS

Cross-sectional data from 7461 British men surveyed in 5 population subgroups. We tested interactions on both additive and multiplicative scales for a syndemic of violence/criminality (VC), sexual behavior (SH), and substance misuse (SM) according to the presence of CA and adult traumatic life events; mediation analysis of path models; and partial least squares path modeling, with PSD as outcome.

RESULTS

Multiplicative synergistic interactions were found between VC, SH, and SM among men, who experienced CA and traumatic adult life events. However, when disaggregated, only SM mediated the pathway from CA to PSD. Path modeling showed traumatic life events acted on PSD through the syndemic and had no direct effect on PSD. Higher syndemic scores and living in areas of deprivation characterized men with PSD and CA.

CONCLUSIONS

Our findings support a broad division of PSD into cases due to (i) biological/inherent causes, and (ii) social determinants, the latter including a syndemic pathway determined by CA. Preventive strategies should focus primarily on preventing adverse effects of CA on developmental pathways which result in PSD. Single component prevention strategies may prevent triggering effects of SM on PSD during adolescence/early adulthood among vulnerable individuals due to CA. Future research should determine applicability and transferability of interventions based on these findings to different populations, specifically those experiencing syndemics.

Gender-based violence syndemics in global health: A systematic review

Global guidance indicates that protections for gender and equity issues, such as gender-based violence (GBV), should be mainstreamed across sectors. One novel strategy that can be leveraged to illustrate the cross-cutting impacts of GBV is to investigate GBV syndemically. This systematic review identified, evaluated, and synthesized quantitative studies conducted in LMICs that tested syndemic theories involving GBV. A systematic search of the peer-reviewed literature was conducted in Medline, Global Health, Scopus, Anthro Source, Anthropology Plus, Web of Science, PsychInfo, and Gender Watch. Peer-reviewed empirical research published in English that used quantitative methods to test syndemic theories involving GBV in LMICs were included. 4068 references were retrieved, 2160 studies were screened against their titles/abstracts, and 227 studies were assessed for full text eligibility. Overall, 45 studies met the inclusion criteria. Most articles conceptualized GBV as an exposure that clustered with other epidemics. More than half of the evidence base investigated combinations of GBV, mental health, substance use, and HIV/AIDS. Research articles investigating the SAVA syndemic among men who have sex with men (MSM) and transgender women provided the strongest evidence, particularly in India. Notable analytical gaps pertained to GBV measurement challenges and statistical approaches to test contextual factors in LMICs. The current evidence base is predominantly focused on GBV syndemic models that inform response/harm mitigation efforts rather than prevention. Future research should concentrate on how the political environment perpetuates clustering and interactions, expanding the contexts studied beyond upper middle-income countries, and improving methodological rigor in terms of GBV measurement.

A historical syndemic? The impact of synergistic epidemics of measles and scarlet fever on life expectancy in Victoria, Australia (1860s-1870s)

OBJECTIVES

To explore whether synergistic epidemics of measles and scarlet fever in 1860s-1870s Victoria, Australia could be characterized as syndemics, we apply the methods of Sawchuk, Tripp, and Samakaroon (Social Science & Medicine 2022, 295, 112956) to quantify the impact of each of the two major co-occurring epidemic events (1867, 1875) in terms of life expectancy (LE) changes. Sawchuk et al. posit the presence of a harvesting effect, indicated by a statistically significant increase in LE in the immediate post-epidemic "fallow period", as a criterion for identification of a historical syndemic. We test an alternate hypothesis that the same methods can identify a short-term scarring effect.

MATERIALS AND METHODS

Using annual age- and cause-specific death statistics and census population data, we constructed abridged period life tables for baseline period, potential syndemic year, and "fallow" year for each of the two periods (1860s and 1870s). We compared LE at birth using Z-tests. We decomposed age-cause-specific mortality according to Arriaga's method to identify age-and cause-specific contributions to LE change.

RESULTS

LE was significantly lower than baseline (1864-1865) in 1867 but not in the "fallow" year (1869). LE in 1875 and the 1878 "fallow" year were both significantly below baseline (1871-1873). Age-cause-specific decomposition showed similar patterns for 1867 and 1875 for measles and scarlet fever combined effects.

DISCUSSION

Evidence of a scarring effect following the 1875 measles/scarlet fever combined peak supports the interpretation of this event as a syndemic. We suggest the short-term scarring effect can be a useful additional criterion for identifying historical syndemics.

Using a Syndemics Perspective to (Re)Conceptualize Vulnerability during the COVID-19 Pandemic: A Scoping Review

Syndemics theory has been applied to study interactions between biomedical and social factors leading to the clustering of diseases. Because syndemics theory focuses on interactions that enhance risk, the concept of vulnerability is central to this approach. We conducted a scoping review to better understand how this theoretical framework helped to define, operationalize, and tackle issues of vulnerability during the COVID-19 pandemic. Original research, reviews, and opinion pieces elaborating on syndemics, vulnerability, and COVID-19, published between December 2019 and October 2022 and available from PubMed, were eligible. We analyzed 40 records and identified three framings of syndemics operating during this period: (1) interactions between COVID-19, diseases/health conditions, and specific social factors; (2) interactions between COVID-19 and social determinants of health; and (3) impacts of COVID-19 on specific populations. Emerging conceptualizations described vulnerability to COVID-19 as a systemic issue, explained the impact of COVID-19 control measures on increased vulnerability, and presented COVID-19 as a syndemic on its own. However, this theory's potential for deepening our understanding of vulnerability during this pandemic was constrained by superficial explorations of the interactions between biomedical and social spheres, and insufficient theoretical and methodological support from the social sciences.

A syndemic of inequitable gender norms and intersecting stigmas on condom self-efficacy and practices among displaced youth living in urban slums in Uganda: a community-based cross-sectional study

BACKGROUND

Adverse socio-cultural factors compromise the implementation of HIV prevention strategies among displaced youth. While condoms are an affordable and effective HIV prevention strategy for youth, stigma and inequitable gender norms may constrain condom self-efficacy (i.e., knowledge, intentions, and relationship dynamics that facilitate condom negotiation) and use. Further, knowledge of contextually appropriate HIV prevention approaches are constrained by limited understanding of the socio-cultural conditions that affect condom self-efficacy and use among displaced youth. Guided by syndemics theory, we examine independent and joint effects of adverse socio-cultural factors associated with condom self-efficacy and use among displaced youth living in urban slums in Kampala, Uganda.

METHODS

We conducted a community-based cross-sectional survey of displaced youth aged 16-24 years living in five slums in Kampala. We used multivariable logistic regression and multivariate linear regression to assess independent and two-way interactions among adverse socio-cultural factors (adolescent sexual and reproductive health-related stigma [A-SRH stigma], perceived HIV-related stigma, and beliefs in harmful inequitable gender norms) on condom self-efficacy and recent consistent condom use. We calculated the prevalence and co-occurrence of adverse socio-cultural factors; conducted regression analyses to create unique profiles of adverse socio-cultural factors; and then assessed joint effects of adverse socio-cultural factors on condom self-efficacy and practices.

RESULTS

Among participants (mean age: 19.59 years; SD: 2.59; women: n = 333, men: n = 112), 62.5% were sexually active. Of these, only 53.3% reported recent consistent condom use. Overall, 42.73% of participants reported two co-occurring adverse socio-cultural factors, and 16.63% reported three co-occurring exposures. We found a joint effect of beliefs in harmful inequitable gender norms with high A-SRH stigma (β = - 0.20; p < 0.05) and high A-SRH stigma with high perceived HIV stigma (β = - 0.31; p < 0.001) on reduced condom self-efficacy. We found a multiplicative interaction between high A-SRH stigma with high perceived HIV stigma (aOR = 0.52; 95% CI 0.28, 0.96) on recent consistent condom use. Additionally, we found that condom self-efficacy (aOR = 1.01; 95% CI 1.05, 1.16) and safer sexual communication (aOR = 2.12; 95% CI 1.54, 2.91) acted as protective factors on inconsistent condom use.

CONCLUSIONS

Displaced youth living in urban slums exhibited low consistent condom use. Intersecting stigmas were associated with lower condom self-efficacy-a protective factor linked with increased consistent condom use. Findings highlight the importance of gender transformative and intersectional stigma reduction approaches to increase sexual agency and safer sex practices among Kampala's slum-dwelling displaced youth.

The ecosyndemic framework of the global environmental change and the COVID-19 pandemic

The ecosyndemic theory combines the concept of 'synergy' with 'epidemic' and the term "eco" implies the role of the environmental changes. Each of the conditions enhances the negative impacts of the other in an additive way making our society more vulnerable and heightening individual risk factors. In this study, we analyze the mutually reinforcing links between the environment and health from the complexity angle of the ecosyndemic theory and propose the characterization of the COVID-19 pandemic as ecosyndemic. We use the term 'ecosyndemic' because the global environmental change contributes to local-scale, regional-scale and global-scale alterations of the Earth's systems. These changes have their root causes in the way that people interact with the physical, chemical, and biotic factors of the environment. These interactions disturb nature and the consequences have feedbacks in every living organism.

A Pilot Study of Polysubstance Use Sequences across the Lifespan among Assiniboine and Sioux People Who Use Injection Drugs

Compared with other racial/ethnic groups in the United States, American Indians/Alaska Natives have the highest rates of acute Hepatitis C Virus (HCV) infection, the highest HCV-related mortality, and one of the fastest climbing rates of drug overdose deaths involving stimulants. In this pilot study, a life history calendar was administered to Indigenous people who use injection drugs (IPWIDs) to understand sequences of polysubstance use across the lifespan. 40 IPWIDs completed a questionnaire and life history calendar. Social sequence analysis was used to examine patterns in sequential phenomena among substances reported over years of the lifespan. Most participants (55%) began injecting substances before the age of 21, 62.5% shared syringes with others, and 45% had ever been diagnosed with HCV. An appreciably large increase in the use of stimulants occurred between the year prior to and following injection initiation (33% to 82%). A three-cluster solution distinguished younger IPWIDs transitioning into polysubstance use involving stimulants and/or narcotic analgesics from adults using narcotic analgesics with stimulants over longer periods of time, and adults most focused on stimulant use over time. Findings from this pilot study contribute to an understanding of how methamphetamine injection plays a role in the HCV epidemic among IPWIDs.

Type 2 diabetes and depressive symptoms in the adult population in Mexico: a syndemic approach based on National Health and Nutrition Survey

BACKGROUND

The syndemic approach allows the analysis of clusters of diseases that affect a population in contexts of geographic, social and economic inequalities at the same moment and time. This study aims to analyze, from a syndemic perspective, the relationship between type 2 diabetes (T2D) and depressive symptoms in Mexican adults and its association with individual, contextual and structural factors.

METHODS

Observational, cross-sectional study based on secondary data from Mexico's National Health and Nutrition Survey 2018-19. The sample of this study consisted of 16 835 adults, which represented a total of 78 463 734 persons aged ≥ 20 years. Bivariate descriptive analyses were performed and logistic regression models were estimated to analyze the association between T2D and depressive symptoms with various co-variables. In addition, interactions between T2D and depressive symptoms with obesity, educational level, and socioeconomic status were tested.

RESULTS

In the study population, 12.2% of adults aged 20 years and older self-reported having T2D, 14.7% had depressive symptoms and 2.8% had both diseases. There was a statistically significant relationship between T2D and depressive symptoms. The prevalence of T2D and depressive symptoms was higher compared to people who did not have these two conditions. Obesity increased the probability of having T2D, while violence was statistically associated with people having depressive symptoms. A low level of education increased the odds ratio of having T2D and depressive symptoms.

CONCLUSION

The availability of analytical frameworks such as the syndemic perspective could help to identify areas of opportunity for decision making and actions for population groups that-because of their individual, contextual and structural disadvantages-are at greater risk of experiencing poorer health outcomes due to the presence of T2D and depressive symptoms.

Pandemics, past and present: The role of biological anthropology in interdisciplinary pandemic studies

Biological anthropologists are ideally suited for the study of pandemics given their strengths in human biology, health, culture, and behavior, yet pandemics have historically not been a major focus of research. The COVID‐19 pandemic has reinforced the need to understand pandemic causes and unequal consequences at multiple levels. Insights from past pandemics can strengthen the knowledge base and inform the study of current and future pandemics through an anthropological lens. In this paper, we discuss the distinctive social and epidemiological features of pandemics, as well as the ways in which biological anthropologists have previously studied infectious diseases, epidemics, and pandemics. We then review interdisciplinary research on three pandemics–1918 influenza, 2009 influenza, and COVID‐19–focusing on persistent social inequalities in morbidity and mortality related to sex and gender; race, ethnicity, and Indigeneity; and pre‐existing health and disability. Following this review of the current state of pandemic research on these topics, we conclude with a discussion of ways biological anthropologists can contribute to this field moving forward. Biological anthropologists can add rich historical and cross‐cultural depth to the study of pandemics, provide insights into the biosocial complexities of pandemics using the theory of syndemics, investigate the social and health impacts of stress and stigma, and address important methodological and ethical issues. As COVID‐19 is unlikely to be the last global pandemic, stronger involvement of biological anthropology in pandemic studies and public health policy and research is vital.