Nine percent of South African adolescents report being given illicit substances on school property , and school-based initiatives have had documented success in preventing alcohol and cigarette in South Africa . Implementing interventions near heroin hangouts reduced injection heroin use in Tanzania . Schools and the other settings where people are smoking heroin in South Africa may be important sites for intervention. Because MAT prevents initiation of injection drug use by decreasing the number of active heroin initiators and behavioral interventions may deter people who inject heroin from initiating others , MAT and/or behavioral interventions targeting people who smoke heroin may also reduce the number of smoked heroin initiators and initiations. Although the largest qualitative study of smoked heroin in South Africa to date, this study has limitations. Participants were men in substance use treatment who smoked heroin, and caution must be taken in generalizing these findings to other users of heroin, including people who inject heroin and women. Although participants commented on female trajectories into smoked heroin use and the unique role of intimate partners for initiating women, we were unable to access women’s lived experiences firsthand. Because of the interplay between gender and substance use , sex , and HIV transmission in Africa , research and interventions will likely need to tailored to women. Participants’ experiences may also differ from people who are actively smoking heroin, some of whom may lack the ability to pay for or otherwise access substance use treatment. All participants completed at least some secondary school, and any planned school-based prevention program may not be accessible to people at risk of initiating smoked heroin who do not attend school. Lastly, as a qualitative study, certain important details regarding initiation of the drug – such as age at first use and duration of substance use – were not captured systematically. It will be useful to explore these and other factors in epidemiological studies. Notwithstanding these limitations, we identified several pathways to smoked heroin use in South Africa and characterized social influences on initiation. With many parallels to other heroin epidemics in Africa,wholesale vertical grow manufacturer international cooperation and coordination in the scale-up of MAT, harm reduction services, and other resource-conscientious interventions are recommended.

However, interventions targeting injection drug use, in this context, may not reach people who smoke heroin. Only by understanding the risk environments of smoked heroin will we be able to target interventions to prevent smoked heroin use, prevent transition to injection use, and mitigate other social harms affecting the people who smoke heroin and their communities.Adolescence is a developmental period between childhood and adulthood characterized by marked physiological, psychological, and behavioral changes. Adolescents experience rapid physical growth, sexual maturation, and advances in cognitive and emotional processing . These changes coincide with increases in substance use, with alcohol being the most widely used illegal substance among adolescents . National survey data indicate that 33% of 8th grade students have tried alcohol, and this percentage increases to 70% among 12th graders . Of greater concern is the increase in heavy episodic drinking where prevalence rates increase from 6% to 22% for 8th and 12th grades, respectively , as heavy episodic drinking during adolescence is associated with numerous negative effects on adolescent health and well being, including risky sexual behaviors , hazardous driving , and alterations in adolescent brain development . During adolescence, the brain undergoes significant changes, and a recent longitudinal neuroimaging study suggests that heavy episodic drinking during this developmental period alters brain functioning . Squeglia and colleagues examined the effects of heavy episodic drinking on brain function during a visual working memory task, comparing brain activity in adolescents at baseline and again at follow-up to compare brain activity in those who transitioned into heavy drinking during adolescence to demographically matched adolescents who remained nondrinkers. Adolescents who initiated heavy drinking exhibited increasing brain activity in frontal and parietal brain regions during a visual working memory task compared to adolescents who remained nondrinkers through follow-up, who showed decreasing frontal activation, consistent with studies in typical development . Thus, adolescent heavy episodic drinking may alter brain functioning involved in working memory; however, additional longitudinal studies are needed to explore the effects of alcohol on neural correlates of other vital cognitive processes, such as response inhibition. Response inhibition refers to the ability to withhold a prepotent response in order to select a more appropriate, goal-directed response . The neural circuitry underlying response inhibition develops during adolescence , and as such, brain response during inhibition changes during adolescence . Briefly, cross-sectional research indicates that brain activation during response inhibition transitions from diffuse prefrontal and parietal activation to localized prefrontal activation .

Longitudinal studies report that atypical brain responses during response inhibition, despite comparable performance, is predictive of later alcohol use , substance use and dependence symptoms , and alcohol-related consequences . Together, these findings indicate that neural substrates associated with response inhibition change over time and abnormalities in development may contribute to later substance use. To this end, the current longitudinal fMRI study examined the effects of initiating heavy drinking during adolescence on brain activity during response inhibition. We examined blood oxygen level dependent response during a go/no-go response inhibition task prior to alcohol initiation , then again on the same scanner approximately 3 years later, after some adolescents had transitioned into heavy drinking. Based on our previous findings , we hypothesized that adolescents who transition into heavy drinking would show reduced BOLD response during response inhibition prior to initiating heavy drinking followed by increased activation after the onset of heavy episodic drinking, as compared to adolescents who remained non-users. By identifying potential neurobiological antecedents and consequences of heavy episodic drinking, this study will extend previous research on the effects of alcohol on brain function and point to risk factors for heavy episodic drinking during adolescence. The present longitudinal neuroimaging study examined the effects of initiating heavy drinking during adolescence on brain responses during response inhibition. We hypothesized, based on previous findings , that adolescents who transition into heavy drinking would show reduced BOLD response during response inhibition prior to initiating heavy drinking followed by increased activation after the onset of heavy episodic drinking, as compared to adolescents who remained non-drinkers. Examining a longitudinal neuroimaging sample of youth both preand post-alcohol use initiation allowed us to address the etiology of neural pattern differences. Although group × time effect sizes were small, our findings suggest that differential neural activity patterns predate alcohol initiation and also arise as a consequence of heavy drinking. We found significant drinking status × time interactions in a number of distinct and reproducible brain regions commonly associated with response inhibition. Prior to initiating substance use, adolescents who initiated heavy use showed less BOLD activation during inhibitory trials in frontal regions, including the bilateral middle frontal gyri, and non-frontal regions, including the right inferior parietal lobule, putamen, and cerebellar tonsil, compared with those who continued to abstain from alcohol use.

This pattern of hypoactivity among youth who later initiated heavy drinking during response inhibition is consistent with studies showing decreased activity during response inhibition predicts later alcohol use and substance use . Indeed, change in BOLD response contrast over time in the right middle frontal gyrus was associated with lifetime alcohol drinks at follow-up. Together, these findings provide additional evidence for the utility of fMRI in identifying neural vulnerabilities to substance use even when no behavioral differences are apparent. At follow up, adolescents who transitioned into heavy drinking showed increasing brain activation in the bilateral middle frontal gyri, right inferior parietal lobule, and left cerebellar tonsil during inhibition; whereas, non-drinking controls exhibited decreasing brain activation in these brain regions. These regions have been implicated in processes of stimulus recognition, working memory, and response selection ,wholesale vertical grow supplier all of which are critical to successful response inhibition. Indeed, neuroanatomical models of inhibitory control highlight the importance of frontoparietal attentional control and working memory networks . These models posit that inhibition and cognitive control involve frontoparietal brain regions when detecting and responding to behaviorally relevant stimuli. Thus, findings suggest that heavy drinkers recruit greater activity in these neural networks in order to successfully inhibit prepotent responses. Given the longitudinal nature of the current study, it is important to consider our findings in the context of typical adolescent neural maturation. During typical neural maturation, adolescents exhibit less activation over time, as neural networks become more refined and efficient . This typical pattern of neural maturation occurred among adolescents who remained nondrinkers. Adolescents who transitioned into heavy drinking showed the opposite pattern – increasing activation despite similar performance, suggesting that alcohol consumption may alter typical neural development. The current findings should be considered in light of possible limitations. Although heavy drinking and non-drinking youth groups were matched on several baseline and follow-up measures, heavy drinking youth reported more cannabis, nicotine, and other illicit drug use at follow-up. Differential activation remained significant after statistically controlling for lifetime substance use and such differences may contribute to our findings. Further, simultaneous substance use might be associated with these results. Future research should explore the effects poly substance use during the same episode compared to the effects of heavy drinking on neural responses. It is also important to note that adolescence is a period of significant inter-individual differences in neural development, and as such, we matched self-reported pubertal development and age at baseline and follow-up to address this issue.

For the current sample, histograms of age distributions at baseline and follow-up are provided in Online Resource 1. Again, our groups were well matched on these variables; however, additional longitudinal research to examine the effects puberty and hormonal changes on neural functioning and response inhibition are needed. In summary, the current data suggest that pre-existing differences in brain activity during response inhibition increase the likelihood of initiating heavy drinking, and initiating heavy alcohol consumption leads to differential neural activity associated with response inhibition. These findings make a significant contribution to the developmental and addictive behaviors fields, as this is the first study to examine neural responses differences during response inhibition prior to and following the transition into heavy drinking among developing adolescents. Further, we provide additional support for the utility of fMRI in identifying neural vulnerabilities to substance use even when no behavioral differences are apparent. Identifying such neural vulnerabilities before associated behaviors emerge provides an additional tool for selecting and applying targeted prevention programs. Given that primary prevention approaches among youth have not been widely effective, it is possible that targeted prevention programs for youth who are at greatest neurobiological risk could be a novel, effective approach. As such, our findings provide important information for improving primary prevention programs, as well as answering the question of whether neural differences predate alcohol initiation or whether differences arise as a consequence of alcohol use. Although researchers in sociology, cultural studies, and anthropology have attempted, for the last 20 years, to re-conceptualize ethnicity within post-modernist thought and debated the usefulness of such concepts as “new ethnicities,” researchers within the field of alcohol and drug use continue to collect data on ethnic groups on an annual basis using previously determined census formulated categories. Researchers use this data to track the extent to which ethnic groups consume drugs and alcohol, exhibit specific alcohol and drug using practices and develop substance use related problems. In so doing, particular ethnic minority or immigrant groups are identified as high risk for developing drug and alcohol problems. In order to monitor the extent to which such risk factors contribute to substance use problems, the continuing collection of data is seen as essential. However, the collection of this epidemiological data, at least within drug and alcohol research, seems to take place with little regard for either contemporary social science debates on ethnicity, or the contemporary on-going debates within social epidemiology on the usefulness of classifying people by race and ethnicity . While the conceptualization of ethnicity and race has evolved over time within the social sciences, “most scholars continue to depend on empirical results produced by scholars who have not seriously questioned racial statistics” . Consequently, much of the existing research in drug and alcohol research remains stuck in discussions about concepts long discarded in mainstream sociology or anthropology, yielding robust empirical data that is arguably based on questionable constructs .