Our findings showed that females in this sample were more likely to be MA dependent and to use MA more heavily than males, and this is consistent with prior studies (Kim and Fendrich, 2002, Dluzen and Liu, 2008, Gonzales et al., 2008). Reasons for this difference are unknown, but biological factors may well be involved. For example, females have been shown to be more vulnerable to the reinforcing effect of psychostimulants (Lynch et al., 2002, Roth et al., 2004), and experience MA as more euphorigenic than males during the follicular, estrogen-related phase of their menstrual cycle (Lynch et al., 2002). Females also have less neuronal toxicity as measured by the severity of brain white matter hyperintensities (Bae et al., 2006) and have less dopamine release in response to psychostimulant administration (Munro et al., 2006). Environmental and/or psychosocial factors are also very likely to be important - specifically, since our study focused on a hospitalized MA sample, factors that differentially influence men and women with respect to entering into inpatient drug-treatment. For example, sex differences in responsibilities for the care of
