In the context of decreasing or plateauing HIV incidence among multiple risk groups in United States, new HIV infections among gay, bisexual, and other men who have sex with men (MSM) continue to rise. Syndemic theory has become a well-established framework for the explanation of how individual experiences and social conditions influence both an individual’s disease experience and the distribution of disease across populations. This framework is currently defined as “a set of enmeshed and mutually enhancing health problems that, working together in a context of deleterious social and physical conditions that increase vulnerability, [and] significantly affect the overall disease status of a population.”1 An important and robust body of literature has been amassed investigating syndemic burden and its association with HIV status, HIV incidence, HIV-related sexual risk behaviors, and more recently, antiretroviral (ART) medication adherence and viral suppression among HIV-positive MSM. Many of the studies that comprise this literature have several things in common. They are mostly focused on enmeshed individual-level risk factors; that is, this literature largely focuses on co-occurrence of these health problems and the increased vulnerability to HIV that may develop as a result. Even more importantly, most of these studies focused on a small subset of these risk factors: childhood sexual abuse, depression, intimate partner violence, polydrug use. These studies also largely ignore the synergy (defined as biological interaction on the additive scale or deviations from additivity) implied in the mutually enhancing language of this framework. Finally, this literature is also unable to account for the “deleterious social and physical conditions” that give context to the individual-level burden. Taken together, the body of studies present an important but not fully realized use of this framework. This dissertation seeks to investigate all three major facets of the syndemic framework: the individual-level co-occurring syndemic factors, the implied synergy, and the social and physical conditions that surround and influence the individual. It will do so in three steps, broadly defined by a systematic literature review followed by two analytic papers. The literature review will serve as a guide to the syndemics literature among MSM, and will identify the constellation of experiences that have been identified as syndemic factors. The identified experiences will be used to guide the first analytic paper, which will incorporate those experiences into syndemic burden, which will then be modeled using latent class modeling (LCA) to investigate if there are any patterns of syndemic burden that may be important to intervention development. This first analytic paper will also explicitly investigate synergy by calculating the attributable proportion due to interaction (AP). Finally, the second analytic paper will incorporate the “deleterious social and physical conditions” using multilevel latent class modeling (MLCA).

The purpose of this dissertation is to test how growth, reproduction, and immune functioning interact in two populations of adult women residing in vastly different socio-economic and ecological environments, the Kalunga quilombo in Brazil, and the United States of America. The presence of life history trade-offs was tested to determine how the different envirnonments, and socio-ecological contexts of the populations were creating differential risks for health and reproductive outcomes, and life history trade-offs. I hypothesized that the Kalunga people, living in very difficult and harsh conditions, would experience greater amounts of, and more severe, life history trade-offs than the U.S. women. I also hypothesized that in both populations, syndemic interactions between health outcomes, and the larger macro-social conditions, would influence stature, immune functioning, and reproduction. Additionally, these syndemic interactions would perpetuate poor health and reproductive outcomes within the entire Kalunga population, and portions of the U.S. population. I collaborated with the University of Brasilia to collect data adult women from in the Kalunga quilombo in Goiás State, Brazil (n=38) via semi-structured interviews in 2016. In addition, these data were compiled with reproductive, demographic, anthropometric, biological, and socio-economic data collected from adult Kalunga women in 2015 by the University of Brasilia’s Department of Genetics and Morphology. Demographic, anthropometric, biological, and socio-economic data recorded in the National Health and Nutrition Examination Survey (NHANES) 2005-2006 from adult U.S. women was also analyzed. Life history traits were measured through stature (cm), Immunoglobulin E (IgE; kU/l), and reproductive variables (fertility, and reproductive ages) for both populations. My results demonstrated that life history trade-offs impact diverse populations. I found evidence to support life history trade-offs occurred between stature and fertility, and stature and reproductive ages, in both populations. However, my results also indicated that the socio-economic, and ecological, conditions of both populations heavily influenced stature and reproduction in the women. Life history trade-offs were not observable between immune functioning and fertility in the Kalunga population, and not readily evident in the U.S. sample. The positive associations between IgE and fertility in the U.S. women indicate that while life history trade-offs may be suggested, other biocultural variables including: low income, ethnicity, education, and body size, are stronger influences on immune functioning, and fertility, in the U.S. women. Though the Kalunga women had a history of infectious and parasitic diseases, and lived in conditions of poor sanitation and poverty, they had multiple ways of mitigating the stresses of their everyday life. The shared socio-ecological conditions of their community decreased the deprivations they experienced, reduced the disabilities they felt from their health statuses, and was reflected in relative homogeneity of their lived experience. In contrast, the U.S. population was dictated by disparities. Poor health and reproductive outcomes were concentrated disproportionately in low-income, less educated, and/or minority ethnicity status, women. The findings of this dissertation have important implications for applied anthropology and the study of life history theory. My results demonstrate that Western lifestyles must be considered as instigators of life history trade-offs, and life history scholarship in humans must also focus on populations living in these conditions. Additionally, the secular changes resulting in lowered ages of menarche in U.S. women could lead to future poor health outcomes. As the Kalunga transitions into a more Western lifestyle, they are at risk for disparities within their population. It is imperative for applied anthropologists to be engaged in addressing the immune, nutritional, and psychosocial stressors within populations that perpetuate disparities, and instigate and/or exacerbate life history trade-offs.

People who experience structural violence are an increased risk for health conditions including HIV and Hepatitis C. Particularly they are at greater risk for experiencing known syndemic interactions between these two chronic infectious diseases. The risks are mediated bio-socially through the ways that structural inequality increases social and biological vulnerability to illness and suffering. Structural inequalities, or experiences of structural violence shape environments of risk; environments of risks increase social and biological vulnerability to the structures of risk promoting syndemic interactions between biological, behavioral, and psychological conditions. The lived experiences of people diagnosed with a combination of HIV, HCV, and mental health conditions (MHC) (e.g., mood disorders and depression) are, however, thus far understudied. Many aspects and consequences of structural violence and social suffering; poverty, homelessness, substance use, lack of access to healthcare, and structural risks for HIV, HCV, MHC and interactions between the three. Through this mixed-methods, primarily qualitative, ethnographic fieldwork with individuals in the Boston area living with HIV, HCV, or both HIV and HCV, or suffering from MHC I ethnographically explore people’s perceptions of their vulnerability to these syndemic interactions. I also investigate their experiences of being at-risk for these conditions. Through this process, I seek to illuminate individuals’ understandings of the impact structures of risk (i.e., substance use, food insecurity and unstable housing) have on lived experiences with HIV/HCV, HIV/MHC, and HCV/MHC syndemics. The perceptions of the lived realities of disease-behavioral-psychological interactions and health consequences are analyzed in the context of substance use. Substance use’s biological and social dimensions have a role in promoting syndemic interactions for each of the syndemics experienced within this population. Therefore, substance use is a syndemogenic factor because of its role as a mediator for environments of risks, and as a structural risk factor in all three of these syndemics. These interactions, and consequential health outcomes, in sufferers’ own words, enrich the landscape of syndemics research, producing a clearer picture regarding the structures of risks affecting this vulnerable group in the greater Boston area.

Existing literature provides support for a possible syndemic among adult film actresses. Multiple studies emphasize that a combination of economic, social, and cultural issues work together in tandem to synergistically amplify HIV/STI risk in this vulnerable population. It is critical to acknowledge how the detrimental effects of the high prevalence of substance abuse, psychological distress, intimate partner violence, and childhood sexual abuse work together in a system to heighten HIV/STI risk among adult-film actresses. Additionally, issues including the retrogressive dynamic and unequal power and hegemony in the industry function as facilitators which lower the overall health profile of adult-film actresses. It is therefore important to explore the additive relationship between multiple psychosocial health problems of HIV/STI risk among adult-film actresses. The goals of this study are to explore the tenets of the adult-film actress syndemic and use the ecosocial model to organize the associations between psychosocial health problems and HIV/STI risk. This thesis utilizes a two-phase, transformative explanatory sequential mixed methods design which combines multivariable logistic regression and ethnography to understand HIV/STI risk and how depression, childhood sexual abuse, intimate partner violence, and substance use are embodied in the daily lives of adult-film actresses. The quantitative component of this study utilized data collected from a survey of 134 adult- film actresses from the United States. Statistically significant relationships were seen between the independent variables (psychosocial problems) and the dependent variables (i.e., number of personal sex partners, perception of HIV risk, and participation in other sex work). Other relevant quantitative findings included the statistically significant relationships between the syndemic variable and multiple dependent variables. The second component of this study consisted of an ethnography that addressed the theoretical deficiencies in the quantitative phase. Eight adult-film actresses living in the United States were recruited through a testing agency located in Florida, a non-profit located in California, and social networking sites (You tube, Twitter, Facebook, and MySpace) and were then interviewed by phone. The ethnography provided substantive information on the processes which potentially undergird and fuel the syndemic among adult-film actresses including the link between traumatic childhood experiences, substance use and depression. Additional qualitative findings also included elucidating how components of occupational culture increase HIV/STI risk among adult-film actresses. Prominent qualitative themes included traumatic childhood experiences, tenuous romantic relationships and multiple rapes. The integration of both phases of this study provide information on how the interplay between micro, meso and macro level factors work together in a system to additively augment HIV/STI risk among adult-film actresses. Findings from this study have the potential to influence risk reduction policies that could improve the lives of adult-film actresses.

The present study investigates the self-care and health maintenance strategies undertaken by individuals from Halton Region, Ontario living with type 2 diabetes and receiving assistance from food acquisition services such as community food re-distribution centres and food banks. This qualitative research project pulls narrative and thematic interview data from 18 semi-structured one-on-one interviews analyzed with syndemic theory and social determinants of health frameworks to demonstrate how clustering non-communicable diseases and social conditions disproportionately affect those in the lowest income category, and interact with each other to exacerbate the negative health effects of each condition alone. The contributions of this study are theoretical and applied. Theoretical contributions augment existing evidence for the study of non-communicable diseases using a syndemic model. The study participants demonstrated syndemic clustering of five conditions: type 2 diabetes, food insecurity, low income, poor mental health, and activity limitation. Further, this study suggests an applied element to the syndemic model through an approach to health and diabetes care that incorporates the whole person as opposed to a single disease as a unit of care. As suggested through the findings of research participant testimony, a diabetes health care centre, in addition to traditional diabetes care, would ideally screen and offer care for the other common clustered conditions listed in the syndemic elements above. Thus, the centre would provide nutrition, physical activity, mental health, and social supports to patients. As well, it is recommended that future research contributes to prevention and treatment of non-communicable diseases through social, political, and economic in form of increasing government and healthcare supports for people living with low-income and food insecurity. / Thesis / Master of Arts (MA) / This study looks at how individuals from Halton Region, Ontario maintain their health while living with type 2 diabetes and reduced access to healthy, fresh food. The project uses interview data from 18 one-on-one interviews to demonstrate how people with low income suffer from poorer overall health. Specifically, five conditions affected the study participants’ health: type 2 diabetes, reduced access to healthy food, low income, poor mental health, and reduced financial or physical access to exercise or activities of daily living (activity limitation). To combat these conditions, this study suggests an approach to health and diabetes care that looks at the whole person. Evidence and participant suggestions indicate a diabetes health care centre that screens and offers care for other common conditions that occur such as the elements listed above, and also provides nutrition care, physical activity, and social support to patients.

<b>Background:</b> Women who inject drugs face vast disparities in health outcomes relative to their counterparts in the general population, most notably in HIV. Intimate partner violence (IPV) victimisation has a detrimental individual effect on women's HIV risk behaviour. Furthermore, IPV often co-occurs with substance use and poor mental health among women in high-income countries, but little is known about the cumulative and interactive effects of these conditions on women's HIV risk behaviour in low- and middle-income countries. This thesis applied an ecological approach guided primarily by syndemics theory to understand influences on women's HIV behavioural outcomes. It examined associations and mechanisms linking IPV, substance use, and depression, with HIV sexual and injecting risk outcomes in the first quantitative study of Indonesian women who inject drugs, the Women Speak Out study. <b>Methods:</b> This study combined community-based participatory approaches and extensive formative research with quantitative survey methods. 731 women, ≥18 years of age, and injecting illicit drugs in the preceding year were recruited using respondent-driven sampling (RDS) from urban settings in Greater Jakarta and Bandung, Indonesia. Network characteristics of the sample were assessed using the RDS software package for Stata 14. Data were analysed using multivariate logistic regressions, marginal effects models, and interaction analyses on the additive and multiplicative scales. The study was conducted in collaboration with the Indonesian Drug User Network. <b>Results:</b> Paper 1: Past-year IPV victimisation doubled the odds of engaging in one or more sexual HIV risk behaviours. Several covariates were associated with higher odds of sexual risk behaviour: HIV-positive status, non-injection crystal methamphetamine (crystal meth) use, low educational attainment, younger age, and being single. Co-occurrence of psychological, physical and/or injurious, and sexual forms of IPV had cumulative effects: sexual risk behaviour was reported by 62% of women who did not experience any form of IPV, but increased to 89% among those exposed to all three forms. Paper 2: Past-year IPV elevated women's odds of receptive syringe sharing. These effects remained after controlling for socio-demographic confounders. Two covariates, injecting illicit pharmaceuticals (vs heroin only) and housing instability and/or homelessness, remained associated with receptive syringe sharing in multivariate analyses. Paper 3: More than 1 in 4 women experienced concurrent IPV, depressive symptoms, and crystal meth use. All three exposures had independent negative effects on HIV sexual risk outcomes. The co-occurrence of all three factors produced a 4-fold increase in rates of survival sex work, 5-fold increase in STI symptomatology, and a 7-fold increase in inconsistent condom use. The joint effect of depressive symptoms and crystal meth use together was greater than the product of the estimated effects of each exposure alone on STI symptomatology, indicating an interaction on the multiplicative scale. Statistically-significant positive additive interaction was detected between IPV victimisation and crystal meth on inconsistent condom use; depression and crystal meth on STI symptomatology and on survival sex work; and IPV and depression on STI symptomatology and survival sex work. <b>Conclusion:</b> This thesis provides new evidence of the individual and cumulative effects of IPV, methamphetamine use, and depression on HIV risk outcomes among Indonesian women who inject drugs. The interaction analyses are the first to empirically test the assertion that these co-occurring conditions interact synergistically to increase drug-using women's HIV risk. This thesis furthers our understanding of how syndemics function within women who inject drugs to produce health disparities, and contributes to the problem theory for HIV risk behaviour in this population. The findings of this study have great public health significance and important implications for future longitudinal research, interventions, and policy.

Since the early 1990s with the AIDS pandemic, there has been an increasing interest on the importance of risky sexual behaviors, especially among men who have sex with men (MSM). An important antecedent for these behaviors is alcohol use. Studies consistently show an increased frequency of both alcohol use and risky sexual behaviors in MSM populations. However, to date, there has not been a precise estimate of the effect size in these diverse populations and a consistent way to measure it. More so, the importance of context is often cited as a source of variability, but is rarely measured in these studies. Contextual factors are different and specific for MSM, as they have been approached by two theories, both of which will be guiding this dissertation: Singer’s Syndemic Theory and Meyer’s Minority Stress Theory. Chapter 1, then presents a comprehensive review of both theories as they apply to alcohol use, risky sexual behaviors, and contextual factors driving them. Chapter 2 answers the first research question about effect sizes through a systematic literature review. The effect sizes or measures of association of these contextual risk and protective factors were summarized using meta-analytic techniques. Using five electronic databases, we identified 26 studies in 26 years (1990–2015), all diverse in terms of sampling techniques, assessment of sexual orientation, operationalization of alcohol use and risky sexual behaviors, contextual factors included, and measurement of effect sizes. Despite this diversity, studies reporting an effect size were pooled and summarized using both descriptive and meta-analytic techniques, as appropriate. Meta-analyses were conducted using Cochrane’s guidelines for generic inverse variance outcomes with random effects. The pooled effects of alcohol use on condomless anal intercourse (CAI; OR 1.73 [95% CI 1.43, 2.10], I2 0%), heavy episodic drinking on CAI (OR 1.88 [95% CI 1.25, 2.81], I2 32%), and heavy episodic drinking on condomless oral sex (OR: 8.00; 95% CI 2.48, 25.81), as well as the effects of substance use, mental health status, violence and victimization, and self-reported HIV status as contextual factors in the pathway between alcohol use and risky sexual behaviors were calculated, reported, and discussed along with study limitations and implications for public health. Chapter 3 answers the second research question regarding a standardized measurement model for effect sizes and the multiple mediation of contextual factors. We used the male subset of Wave IV of the AddHealth dataset to test our hypotheses through structural equation modeling approaches, including measurement analysis with invariance testing, path analysis for direct effects, and multiple mediation analysis through bootstrapping for indirect effects. The AUD scale was invariant between MSM and MSW, but the risky sexual behavior scale was not. For MSM, the standardized direct effect of AUD onto risky sexual behaviors was –1.25 and the standardized total indirect effect of the multiple mediation model was 1.58, 95% CI [1.42, 1.73]. Among the mediators, the strongest indirect effect for any measured or latent mediator was the mental health construct (2.09). We conclude that even though AUD has the same measurement structure for MSM and MSW, its effect on risky sexual behaviors does not operate the same way for these two populations, supporting both causal and contextual behavioral theories. Conclusions are individually discussed, respectively, in Chapters 2 and 3. However, Chapter 4 puts both manuscript conclusions in context and further discusses future implications for public health research, practice, and policy.