Methods: Data for this study come from the National Longitudinal Study of Adolescent Health (Add Health) DNA subsample. Following prior researchers analyzing the genetic subsample of the Add Health (e.g., Haberstick et al., 2005), we removed one twin from each MZ twin pair to provide conservative parameter estimates. The analyses were confined to 1,136 male respondents (Mean age = 21.96, SD = 1.73). A series of structural equation models were calculated employing maximum likelihood estimation specifically examining the interrelationships among genotypic (DAT1, DRD2), neurodevelopmental variables, proximal environmental pathogens and self-control measures. Structural equation models were calculated for three different dependent measures: a polydrug use scale, alcohol problems scale, and drug problems scale.
Results: Findings showed respondents with more DAT1 risk alleles (i.e., 10R alleles), or with more DRD2 risk alleles (i.e., A-1 alleles) had reduced neurocognitive skills and that DAT1 was positively associated with deviant peers. Further, deviant peer affiliations had a positive effect on measures of ADHD, low self-control, and all three outcome variables. Exposure to deviant peers was associated with increased ADHD symptoms, reduced levels of behavior control ultimately polydrug use and problems stemming from the use of alcohol and drugs.
Conclusions and Implications: Study findings suggest exposure to environmental pathogens by males with vulnerable genotypes may begin to differentially set an individual toward the use of multiple drug and substance-related problems. Social work researchers may find that using biosocial models to be consistent with bio-psycho-social reasoning and person-in-environment knowledge. Greater use of experimental-control condition intervention designs that can simultaneously assess biosocial causal relations and inform treatment knowledge on key constructs such as self-control are badly needed. It may be that treatment attention to key mediators along the biosocial liability continuum may preempt or deflect some of the substance-related problem behaviors before they become too severe. Prevention of multiple drug usage and substance-related problems requires knowledge of replicable etiologic processes that are capable of being interrupted in practical ways for long-term sustainability. The present general biosocial conceptual model is an important beginning toward providing increased direction toward that goal.
References Haberstick, B. C., Lessem, J. M., Hopfer, C. J., Smolen, A., Ehringer, M. A., Timberlake, A., et al. (2005). Monoamine oxidase A (MAOA) and antisocial behaviors in the presence of childhood and adolescent maltreatment. American Journal of Medical Genetics, 135B, 59-64.