Psychobiological Issues in Substance Use and Misuse

Philip Murphy, Philip N. Murphy

• Editore: Routledge
• Anno: 2020
• ISBN:
  9781000336412
• Edizione: 1
• Argomento: Psicología
• Categoria: Psicología fisiológica

In this book, Murphy brings together a team of international experts to review cutting-edge scientific literature from the field of psychobiology and related disciplines which addresses important questions and broadens our understanding of substance use behaviours.

The reader is introduced to the multi-faceted nature of substance use and misuse, and its growing need to be discussed across diverse disciplines and perspectives. The book also addresses important questions regarding public policy and professional practice in the context of different social and cultural environments, and comments on the methodological and ethical issues in substance use and misuse. Chapters explore a spectrum of substances, which include: cocaine, alcohol, ecstasy (MDMA), methamphetamine, synthetic cannabinoids, tobacco, ketamine, novel psychoactive substances, and vaping products. The use of these substances poses important questions for science and for society. This book is written to help academics, practitioners, and students in a variety of academic and professional disciplines answer those questions while staying up to date with the psychobiological literature.

This is a vital resource for professionals and upper-level undergraduate and postgraduate students undertaking research in areas related to biological psychology, biology, health studies, and medicine.

1
THE PSYCHOBIOLOGY OF SUBSTANCE USE BEHAVIOURS AND ITS RELATIONSHIP TO PERSONAL AND SOCIAL PSYCHOLOGICAL INTERPRETATIONS OF THESE BEHAVIOURS

Philip N. Murphy, Serge Combaluzier, Derek Heim, and Rebecca Monk

Introduction

This chapter aims to reflect upon the relationship of psychobiological knowledge concerning substance use behaviours to knowledge coming from the domain of social psychology and from clinical psychology practice, with regard to the personal and socially based interpretations which users themselves have of these behaviours. Given the potential range of personal meanings which people may give to their substance use (or misuse), this chapter draws upon the clinical literature with regard to the specific example of what is commonly termed ‘self-medication’ using either prohibited drugs (e.g. heroin) or alcohol. The objective is to be pragmatic in attempting to demonstrate ways in which an enriched and meaningful understanding of such behaviours may be developed, which may then serve in some way to facilitate the development of research questions and appropriate interventions, rather than to pursue a review of contrasting paradigmatic perspectives, such as exist elsewhere [1]. There is also an aspiration to overcome any academic and professional antagonisms which may exist between the different perspectives and disciplines involved in our stated aim, and to demonstrate the strength of contrasting academic perspectives working together. In this respect, it is not our aim to address directly the debate as to whether addiction should be regarded as a brain disease or not [2–5], but to be pragmatic in highlighting the importance of adopting an eclectic perspective on the complex phenomenon of substance using behaviours.

As with other chapters in this volume, relevant literature will be reviewed, but unlike subsequent chapters which concentrate upon producing cutting edge reviews of available findings, it will be necessary in this chapter to look at both established and emerging literature in order to explore potential foundations of a multifaceted approach to facilitating future developments in research, professional practice, and policy. Such a review is timely because advances in our knowledge of the neurological processes and genetic structures related to addictive substance use have given rise to discussion in the scientific literature concerning how substance use behaviours should be conceptualised. The respective contributions of neurobiological, psychobiological, and social/environmental factors have been particularly relevant to these discussions [6–8]. Within this chapter, the term ‘psychobiology’ will be taken to refer to the co-related effects of psychological phenomena such as changes in cognition and mood, and events in the neurobiological substrates related to these phenomena [9]. A considerable overlap with the subject matter of psychopharmacology is to be noted here with regard to pharmacokinetic and pharmacodynamic processes. As such processes may be regarded in a broad sense as biological, with their consequences for drug action having effects on psychological functioning (i.e. on cognitions and behavioural responses), it is difficult and artificial to separate them from a discussion of a psychobiological perspective on substance use. The term ‘social psychology’ will be used to refer to the study of psychological phenomena in relation to social influences. One commonly accepted definition of social psychology describes it as “the scientific study of the ways that people’s behaviour and mental processes are shaped by the real or imagined presence of others” [10]. From this perspective, it is these interpersonal influences which contribute to a person’s interpretation of and attribution of meaning to their behaviour. The next section of this chapter outlines some of the basic elements of psychobiological knowledge which may serve as a foundation for examining the relationship of this discipline to other domains which focus on a substance user’s subjective meanings and their interpretation of their own behaviour.

Psychobiological processes in substance use and misuse

The bioavailability of a drug to the brain is fundamental to its ability to influence cognition, mood, and overt behaviour. From a psychobiological perspective, two important ways in which a consumed drug may influence psychological functioning are through acting in some way on the processes of neurotransmission, and/or changing the structural properties of the brain in a way which has consequences for psychological functioning and overt behaviour. However, before either of these things can occur, the consumed drug has to arrive at sites in the brain. Pharmacokinetic processes associated with the passage of a drug around the body can influence the duration and intensity of such effects arising from any one episode of administration. Detailed accounts of these processes can be found in other texts [11–15] which highlight the importance of such things as route of administration, the disintegration or dissolution of the administered form of the drug, its absorption into the blood circulatory system, its metabolism by enzymes in the liver, and its dissemination to the brain and other organs. In summary therefore, whatever the personal and social psychological significance or meaning of the act of consuming the drug, it is to be expected that these processes will play an important determining role in what is actually experienced by the user.

Two examples will serve to illustrate here the importance of understanding the pharmacokinetic processes which follow the act of administering a drug, as a basis for explaining the range of cognitive and behavioural phenomena associated with its consumption. The lipophilic nature of (-)-Δ9-tetrahydrocannabinol (Δ9-THC), the psychoactive cannabinoid primarily responsible for the subjective effects of cannabis [16–17], facilitates its storage in adipose tissue with subsequent slow release into the circulatory system for further dissemination [18]. Consequently, this may be expected to influence the time course of the effects of cannabis following administration. Between 80% and 90% of a consumed cannabis dose is reported to be excreted from the body within five days of administration [19], although urine samples from chronic users have shown it still to be present 24 days after administration [20]. Evidence for short-term changes in cognitive performance related to cannabis consumption [21–22] and mood disturbances associated with withdrawal from the drug [23–24] suggests that daily activities, interpersonal relationships, and the broader social behaviours of cannabis users will in some way be impacted by its use, so that the pharmacokinetic processes around the dissemination and excretion of the drug will contribute to modulating these effects. Cannabis has been reported to be a drug for which the experience of its use can be subject to social influence and differences in personal meanings [25–26]. However, an appreciation of the pharmacokinetic processes related to the experience of its use provides a different form of knowledge concerning such use which, it may be argued, needs to be remembered alongside reports of subjective experiences and meanings if a full understanding of its use is to be attained.

The second example comes from heroin misuse where self-administration by smoking leads to a lower level of bioavailability of consumed opiate than intravenous (IV) injection [27]. It is frequently reported in the literature that heroin users seek to maximise the cost effectiveness of their purchased supplies due to the financial pressures arising from their use of the drug in their social environment [28–33]. The need to continue heroin consumption may be seen to come from both a craving for the euphoric state experienced through using the drug, and a desire to avoid unpleasant withdrawal symptoms [34–35]. Both of these experiences which reinforce continued heroin use – positively and negatively, respectively – are important at a psychological level, and have bases in biological processes. Knowledge of the differences in bioavailability of consumed opiate, which are related to these different methods of heroin self-administration, provides an important psychopharmacological insight into a significant change in consumption behaviour which has important implications regarding the user’s experience of their social environment, and the potential influence of others on their behaviour. These implications may manifest themselves, for example, in the form of feeling stigmatised as an injecting drug user [36–37] and/or a feeling of belonging to and with a particular social group [38–39]. In a similar way to the previous example concerning cannabis, it may be argued that a complete understanding of such an important change in heroin using behaviour requires an appreciation of both psychobiological and social psychological insights into it.

On arrival at central nervous system neuronal membranes, molecules of a consumed drug may act in one of the several ways summarised in numerous standard psychopharmacological texts [14–15]. One example of such actions would be to mimic the effects of endogenous neurotransmitters, so that the drug would be acting as an agonist for the neurotransmitter which would normally act on the neuronal receptors in question. The consumption of exogenous opiates such as heroin, for example, leads to agonistic effects on receptors for endogenous opiates active within the brain’s pain perception mechanisms [13–15, 40]. Such agonistic effects on the brain’s mechanisms of pain perception, at an elevated level compared to normal neurotransmission, are consistent with self-reports in the literature concerning euphoria experienced by heroin users [35, 41–44], and clearly provide strong positive reinforcement at a subjective level for continued heroin use. They may also form the basis for self-reported episodes of craving for this experience. Such insights into the subjective experiences of using heroin and, by implication, similar insights regarding other drugs, are undoubtedly important to appreciating the overall meaning to the user of their drug using behaviour [38–39]. However, knowledge of the action of a drug at the level of neuronal receptors which contributes to these subjective experiences adds an important dimension to the explanation of the use of a drug for both practitioners and researchers.

The neurobiological substrates of reward for substance use behaviours have been a topic of interest in the literature for several decades [45]. Numerous authoritative reviews now summarise the extensive body of literature describing the role of changes in dopaminergic and other neurotransmitter activity in the mesolimbic reward pathway as providing a neurobiological basis for the reinforcement of substance use behaviours, with the nucleus accumbens being an area of particular relevance [5, 46–48]. In terms of psychological learning theory, as both positive and negative reinforcement are rewarding, this pathway and its associated areas may be seen to support both positive reinforcements for substance use, such as a...