Heritability for MA dependence is moderate (∼30%) (Tsuang et al., 1998, Kendler et al., 2000), and prior studies have weakly supported a host of candidate genes (i.e., BDNF, CYP2D6, GSTM1, SLC22A3, AKT1, GABRG2) as possibly associated with MA abuse or dependence (Bousman et al., 2009). In addition, antisocial characteristics (Herman-Stahl et al., 2007), recent drug (alcohol, nicotine, or cannabis) use, positive attitude toward MA use, and peer pressure toward MA use (Sattah et al., 2002) are associated with MA use disorders. Interestingly, male and female MA users are different with respect to socio-demographics, co-morbidities, pattern of use, and response to treatment (Supplementary table 1). In addition, brain structures and functional activities have also been reported to be different between sexes; male MA users had more hyperintensity of white matter, smaller corpus callosum and less perfusion of parietal and occipital areas compared to females (Bae et al., 2006, Dluzen and Liu, 2008).
