Given the emerging evidence discussed in this review, we propose a theoretical framework (visualized in Figure 1) that extends the hypothesis formulated by de Wit (2). We argue that individuals have a relatively stable capacity for inhibitory control, on the basis of research suggesting a general stability of inhibitory control throughout adulthood following maturation of the prefrontal cortex during adolescence (114, 115). This capacity is likely to be determined by a host of heritable and environmental factors which we have not addressed in detail here [but see (7, 116)], and like all human characteristics there is likely to be wide individual variation. It is also likely that this capacity may be reduced by neurotoxic effects of chronic substance use, particularly if this occurs during adolescence. Such neurotoxic effects have not yet been convincingly demonstrated but they are biologically plausible, and difficult to rule out on the basis of the research that is currently available [see (117)].
