Greater expression of CPP to cocaine likewise has been reported among adolescents relative to adults. For example, adolescent male rats showed CPP at lower doses of cocaine than did adult males (Badanich et al., 2006; Brenhouse & Andersen, 2008; Brenhouse et al., 2008; Zakharova et al., 2008a), with this age difference in sensitivity to cocaine CPP also reported for females (Zakharova et al., 2008b). Cocaine-induced CPP was shown to develop not only at lower doses during adolescence, but also to extinguish more slowly and show greater propensity for reinstatement among adolescents compared to adults (Brenhouse & Andersen, 2008). Reports of enhanced CPP to cocaine among adolescents are not ubiquitous, however, with some studies failing to observe age-related differences (Aberg et al., 2007; Campbell et al., 2000).
