Background Positron Emission tomography (PET) imaging studies have shown that addiction to a number of substances of abuse is associated with a decrease in dopamine D2/3 receptor binding and decreased pre-synaptic dopamine release in the striatum. Some studies have also shown that these reductions are associated with the severity of addiction. For example, in cocaine dependence, low dopamine release is associated with the choice to self-administer cocaine. The goal of the present study was to investigate these parameters of striatal dopamine transmission in heroin dependence and their association with drug seeking behavior. Methods Heroin dependent and healthy control subjects were scanned with [11C]raclopride before and after stimulant administration (methylphenidate) to measure striatal D2/3 receptor binding and pre-synaptic dopamine release. Following the PET scans, the heroin dependent subjects performed heroin self-administration sessions. Results Both striatal D2/3 receptor binding and dopamine release were reduced in the heroin dependent subjects compared to healthy controls. However, neither PET measure of dopamine transmission predicted the choice to self-administer heroin. Conclusions These findings show that heroin addiction, like addiction to other drugs of abuse, is associated with low D2/3 receptor binding and low pre-synaptic dopamine. However, neither of these outcome measures were associated with the choice to self-administer heroin.

Given the high morbidity and mortality among children in low- and middle-income countries as a result of preventable causes, the U.S. government and the United Nations Children's Fund convened an Evidence Summit on Enhancing Child Survival and Development in Lower- and Middle-Income Countries by Achieving Population-Level Behavior Change on June 3–4, 2013, in Washington, D.C. This article summarizes evidence for technological advances associated with population-level behavior changes necessary to advance child survival and healthy development in children under 5 years of age in low- and middle-income countries. After a rigorous evidence selection process, the authors assessed science, technology, and innovation papers that used mHealth, social/transmedia, multiplatform media, health literacy, and devices for behavior changes supporting child survival and development. Because of an insufficient number of studies on health literacy and devices that supported causal attribution of interventions to outcomes, the review focused on mHealth, social/transmedia, and multiplatform media. Overall, this review found that some mHealth interventions have sufficient evidence to make topic-specific recommendations for broader implementation, scaling, and next research steps (e.g., adherence to HIV/AIDS antiretroviral therapy, uptake and demand of maternal health service, and compliance with malaria treatment guidelines). While some media evidence demonstrates effectiveness in changing cognitive abilities, knowledge, and attitudes, evidence is minimal on behavioral endpoints linked to child survival. Population level behavior change is necessary to end preventable child deaths. Donors and low- and middle-income countries are encouraged to implement recommendations for informing practice, policy, and research decisions to fully maximize the impact potential of mHealth and multimedia for child survival and development.

Background Men with HIV who have sex with men (MSM) represent the largest group of people living with HIV/AIDS in the United States. It is important to understand the sexual risk-taking behaviours that may be linked to the transmission of HIV and other sexually transmitted infections in this population. Models of HIV risk that focus solely on personal factors have been demonstrated to be ineffective at explaining risk behaviour. Rather, in order to fully understand sexual risk-taking, it is important to examine the factors linked to high-risk sexual situations and not solely the factors linked to potentially high-risk people. Methods A diverse sample of 100 MSM with HIV completed a 6-week internet-based sex diary that collected detailed information on recent sexual encounters. In total, information on over 250 sexual episodes was collected and analysed. Generalised linear mixed models were used to examine situational predictors of risk episodes. Results Analyses revealed that drug use by self and sex partners (examined individually and together) were positively related to risk episodes. Likewise, having a sex partner met online and having a sexual encounter in a sex party or bathhouse setting was linked to risk episodes. Sexual episodes that involved a sex-partner who was perceived as sexually desirable and those involving communication about HIV and/or condom use with partners each were negatively related to risk. Conclusions Situational factors play an important role in explaining sexual risk-taking among MSM with HIV. Researchers should place a greater focus on drug use and characteristics of sex partners and settings in which sexual behaviours occur as situational predictors of risk in order to comprehensively understand sexual risk-taking in this population.

Researchers have reported that network characteristics are associated with substance use behavior. Considering that social interactions within online networks are increasingly common, we examined the relationship between online network characteristics and substance use in a sample of emerging adults (ages 18–24) from across the United States (N = 2,153; M = 21 years old; 47 % female; 70 % White). We used regression analyses to examine the relationship between online ego network characteristics (i.e., characteristics of individuals directly related to the focal participant plus the relationships shared among individuals within the online network) and alcohol use and substance use, respectively. Alcohol use was associated with network density (i.e., interconnectedness between individuals in a network), total number of peer ties, and a greater proportion of emotionally close ties. In sex-stratified models, density was related to alcohol use for males but not females. Drug use was associated with an increased number of peer ties, and the increased proportion of network members’ discussion and acceptance of drug use, respectively. We also found that online network density and total numbers of ties were associated with more personal drug use for males but not females. Conversely, we noted that social norms were related to increased drug use and this relationship was stronger for females than males. We discuss the implications of our findings for substance use and online network research.

Men who have sex with men (MSM) make up nearly half of all people living with HIV in the United States. The prevalence of the epidemic in this population makes it vitally important to understand the transmission of the infection and to develop methods to prevent its spread. The current study uses longitudinal diary methods to examine relationships between substance use and unprotected anal intercourse in a sample of 158 HIV-positive, mostly ethnic minority MSM. Results indicate that both general substance use and use of specific drugs (i.e., inhalants, cocaine, crack, and club drugs) have a substantial impact on the sexual risk behavior of this population.