Drug addiction and impulsivity : a multi-method investigation of the relationship between drug use and impulsive behaviour

This vast cost of drug addiction, to both individuals and society, continues to fuel research investigating its aetiology and treatment (Gordon et al., 2006). Definitions of addiction often feature a loss of control on reward seeking behaviour, specifically deficits in inhibitory control (impulsive action) and the preference for immediate over delayed rewards (impulsive choice). Indeed, impulsivity is thought to be influential in the onset, progression and propensity to relapse into drug addiction. This thesis utilised a range of methodologies in order to elucidate the role of impulsive behaviour in the progressive pathophysiological process of addiction. Animal models of impulsivity were used to elucidate causality between drug use (specifically, acute nicotine administration) and changes in impulsive behaviour (both impulsive choice and impulsive action). Furthermore, dopaminergic neural mechanisms implicated as mediatory in drug related impulsive choice and action were assessed via dopamine 01 and 02 receptor antagonism. Acute drug administration produced a dose-related increase in both constructs, and findings suggest the independent roles of dopamine 01 and 02 receptors in mediating these behaviours. In the second part of this thesis the wider environmental and sociological context of drug use and impulsive behaviour within a UK prison population were investigated. This population is characterised by elevated impulsivity, and the prominence of their impulsive behaviour and drug use are immensely costly to both themselves and society. Multiple dimensions of behavioural and self- reported impulsivity were assessed in both drug users and non-users, along with their criminal behaviour and psychological functioning. Even within a highly impulsive population, drug users exhibited elevated impulsivity (compared to non users). In recruiting both drug users seeking and not-seeking treatment, the methodology also permitted investigation whether impulsivity could distinguish these groups, as well as the bi-directional relationship between impulsivity in treatment progression. In the third section of this thesis, treatment completers were interviewed on their experience of impulsivity, their past, present and future drug use, and their views on drug treatment. An Interpretative Phenomenological Analysis of the interviews was conducted. Implications are discussed in terms of current research, theory and implications. The findings implicate impulsivity as influential throughout stages of drug addiction and highlight the value of diverse viewpoints in approaching the heterogeneous construct.EThOS - Electronic Theses Online ServiceGBUnited Kingdo