Lack of association between TaqI A1 allele of dopamine D2 receptor gene and methamphetamine abuse or psychosis in Chinese

The reasons why some methamphetamine (MAMP)abusers develop psychotic symptoms, whilst others do not despite prolonged MAMP usage, are not clear. Previous studies examining association between DRD2 TaqI Al and substance abuse or psychosis have produced intriguing results. We set out to examine if the Al plays a major role in predisposing individuals to MAMP abuse and/or MAMP abusers to MAMP psychosis. A total of 412 Chinese MAMP abusers were recruited from a psychiatric hospital and a detention center in Taipei, and assessed with the Diagnostic Interview for Genetic Studies (DIGS). Six of them were diagnosed to have MAMP intoxication with perceptual but not MAMP psychosis. The others were divided into those with a lifetime diagnosis of MAMP psychosis as psychotic abusers (N=154) and those without as non-psychotic abusers (N = 252). There was no significant difference in Al allele frequency between the psychotic and the non-psychotic abusers (44% versus 39%, alpha = 2.4, df = 1, P = 0.12), nor between the MAMP abusers and 432 unrelated normal controls of the same ethnicity (41% versus 43%, alpha = 0.6, df = 1, P = 0.43). The results do not support DRD2 TaqI Al play a major role in either MAMP abuse or MAMP psychosis in Chinese.