Schluger et al. 1998). HPA-axis stimulation plays an important role in the neurobiology of AD, CD and OD. Clinical studies and studies of animal models have shown that modest stimulation of the HPA axis is sought or desired by alcohol- and cocaine-dependent individuals. In contrast, opiate dependents find it aversive, since HPA axis activation is a characteristic of opioid withdrawal (e.g. Bond et al. 1998; Culpepper-Morgan and Kreek 1997; Koob and Kreek 2007; O'Malley et al. 2002). Long-term methadone maintenance treatment normalizes HPA axis activity in heroin addicts (Kreek 1973; Kreek et al. 1983).
