Figure 1. Dopamine and opioid peptide interaction in Schizophrenia and alcoholism.
Left side: Carrying the DRD2 A1 increases the “wanting” of alcohol and in carriers with a low gamma endorphin (DTGE) would augment the risk for psychosis leading them to increased self medication by using alcohol. Right side: Carrying the DRD2 A2 may be protective against alcohol drinking in Schizophrenics. Lack of Gamma Endorphin (DTGE) in utero leads to an over-expression of DRD2 A2. Center: However, some Schizophrenics with the DRD2 A2 allele along with unknown reward gene polymorphisms may use substances due to lack of reward.