Impulsivity

Impulsivity is a multifaceted behavioural trait commonly linked to drug abuse and addiction involving rash or risky behaviour and a strong tendency towards spur-of-the-moment, poorly judged decisions and actions. At its core, impulsivity arises through an inability to adequately suppress or inhibit inappropriate behaviour and by a general intolerance to delayed gratification, a tendency also widely found in abstinent drug addicts. Despite intensive research, however, it remains unclear whether impulsivity arises from neural abnormalities produced by the chronic exposure of individuals to drugs such as alcohol and cocaine (‘state impulsivity’) potentially via interactions with medial temporal lobe and frontal cortical structures (e.g., amygdala, hippocampus, anterior cingulate cortex, orbitofrontal cortex) or whether instead ‘trait impulsivity’ and brain disorders linked to it – for example, attention deficit/hyperactivity disorder (ADHD) – predispose to drug use and addiction. This chapter considers both possibilities from a neural systems and psychological perspective drawing on evidence from animal models and clinical research.