In heroin addicts, a positive correlation was observed between depression-dejection and <i>DRD4</i> CpG5 methylation (r=0.537, P=0.039) whereas there was a negative correlation between drug usage frequency and CpG1 methylation (r=-0.632, P=0.011).
The potential clinical relevance of major polymorphisms of the DRD4 gene are discussed within the context of practical aspects of typical and atypical neuroleptic drug usage within afflicted populations of psychiatric patients.
Furthermore, when the Gene × Environment interaction effects on the increases in affiliations with drug-using companions and vulnerability cognitions were entered into the model forecasting drug use, the Life Stress × DRD4 Status interaction on drug use became nonsignificant in the presence of the risk mechanisms.
We now show that the long form of the DRD4 gene is more frequent in individuals with high quantity/frequency of drug use compared to controls (chi(2) = 5.7, df = 1, P = 0.017, odds ratio = 1.89, CI = 1.1-3.2).