Andrew McBride

Exploring the relationship between genetic and environmental influences on initiation and progression of substance use

Aims To examine the genetic and environmental contributions to the initiation of use and progression to more serious use of alcohol, cigarettes and marijuana during adolescence, and to examine the relationship between initiation and progression of substance use. Design The study used a twin-based design and a new theoretical model, the causal–common–contingent (CCC) model. This allows modelling of the relationship between initiation of use and progression to heavier use as a two-stage model and the examination of genetic and environmental influences on both stages, while taking into account their relationship. Participants The participants consisted of 1214 twin pairs (69% response rate) aged 11–19 years sampled from the UK population-based Cardiff Study of All Wales and North-west of England Twins (CaStANET). Measurements Data on adolescent initiation and progression to more serious use of alcohol, cigarettes and marijuana were obtained using self-report questionnaires. Findings Initiation of alcohol and progression to heavier alcohol use had separate but related underlying aetiologies. For cigarette and marijuana use the relation between initiation and progression to heavier use was stronger, suggesting greater overlap in aetiologies. For all three substances, environmental influences that make twins more similar (common environment) tended to be greater for initiation, while genetic influences were stronger for heavier use. Conclusions These findings have implications for policy decisions aimed at an adolescent and early adult age group. Specifically, these findings suggest that it may be more efficacious to focus alcohol interventions on risk factors for the development of heavier use rather than initiation of use. In contrast, interventions aimed at reducing the initiation of cigarettes and marijuana use may be more appropriate.

Genetic and environmental influences on the relationship between peer alcohol use and own alcohol use in adolescents.

Aims Genetically influenced aspects of adolescent behaviour can play a role in alcohol use and peer affiliation. We explored the correlations between friends alcohol use and adolescent own use with a genetically sensitive design. Design Genetic and environmental factors were estimated on adolescent reports of their friends alcohol use and their own use and problem use of alcohol. The correlations between the genetic and environmental factors that influence friends alcohol use and adolescent own alcohol use and problem use were also estimated. Participants A total of 862 twin pairs aged 11–17 years sampled from the UK population-based Cardiff Study of All Wales and North-west of England Twins (CaStANET). Measurements Data on adolescent own alcohol use and problem use and the alcohol use of their three best friends were obtained using self-report questionnaires. Findings A significant genetic influence was found on adolescent friends alcohol use (about 30%). Significant correlations of 0.60 and 0.70 were found between the genetic influences on friends alcohol use and adolescents own use and problem use of alcohol. Common environmental influences were almost completely correlated for friends alcohol use and adolescents own alcohol use and problem use (0.91 and 0.94). Conclusions There is considerable overlap in the common environmental and genetic factors that contribute to the relationship between adolescents own alcohol use and that of their friends. These findings contribute to understanding of the mechanisms by which friends alcohol use influences adolescent drinking behaviour.

Injecting illicit drugs.

Injecting illicit Drugs is the third book in a new collection from Addiction Press. Addiction Press was set up with the express purpose of communicating current ideas and evidence in this expanding field, not only to researches and practising health professionals, but also to policy makers, students and interested non-specialists. These publications are designed to address the significant challenges that addiction presents to modern society. Injecting drug use is of major concern to both Western and developing nations, causing extensive associated harm at both individual and public health levels. This book provides readers with authoritative an practical information on injecting drug use and the health consequence of this behaviour. As an efficient route of drug administration, the sequelae of injecting illicit drugs can be particularly deleterious in nature. The chapters in this book trace the hazards for the drug injector and promote a harm reduction approach to minimise these risks. Socio-cultural issues are considered, such as the ritualisation of injecting behaviour. Lifestyle characteristics of the injecting drug user are also taken into account. Insights from the user perspective are reflected in the last chapter.

Towards An Holistic Understanding of Injecting Drug Use: An Overview of Needle Fixation

Aims. To establish the existence of needle fixation and provide a theoretical explanation for the phenomenon. Method. By searching published literature using electronic searches, consulting a National Drug Library (ISDD) and snowballing from reference lists in publications related to addiction. Findings. Needle fixation as a phenomenon has been mentioned in the literature since at least 1929 but there is only one published paper devoted to it. Needle fixation is a conditioned response but with a number of different secondary gains which maintain the practice. These include ritual, substitution of non psychoactive substances in the absence of drugs, pain, sexual pleasure and status. Conclusions. Needle fixation should be taken seriously because of the concern about blood borne viruses among injecting drug users and the need to reduce the practice of injecting. A greater understanding of the problem will help in treatment of injecting drug users.

Drug Trends in Wales

This paper describes the evolution of responses to drug related problems in Wales, from the first National Health Service in-patient admissions in the late 1960s until the publication of Forward Together, the Welsh Office strategy for drug and alcohol problems, in May 1996. Service developments are placed in the context of the available data about the nature and extent of drug use across Wales, the particular challenges faced, and the strategies adopted in Britain, in Wales, and at the local level.