Neurobiological and neuropsychological pathways into substance abuse and addictive behaviour

“Addiction,” derived from the Latin verb addicere (meaning “to enslave”), is characterized by the apparent “loss of control” or autonomy over one's behavior. Indeed, the continued use of substances by addicted individuals, despite an apparent awareness of the adverse negative consequences, suggests that addictive behavior may involve deficits in inhibitory control, decision-making and the regulation of affect (Bechara et al., 2001; Fillmore, 2003; Goldstein & Volkow, 2002; Grant et al., 2000; Jentsch & Taylor, 1999; Lubman et al., 2004; Yücel & Lubman, 2007). Recent neuropsychological and neuroimaging studies across a variety of substance-using populations support this notion, implicating impairments in frontal cortical systems critically involved in executive control (Everitt et al., 2001; Rogers & Robbins, 2001). However, an important question that remains is why only a minority of individuals who experiment with addictive substances develop problematic substance-use patterns. This chapter explores this issue from a neuropsychological perspective, specifically focusing on the neuropsychological aspects of addictive behavior (including neuroimaging findings where relevant) under three main sections: (1) Neuropsychological sequelae of specific substances and their role in addictive behaviors. This section will briefly discuss the evidence for specific neuropsychological and neurobiological effects of several major classes of substances including alcohol, cannabis, inhalants, stimulants, opiates and ecstasy. The section ends with a summary of the major findings across the various substances, highlighting consistent evidence for problems in prefrontally mediated functions (such as inhibitory control, decision-making and affect regulation).