Substance use disorders (SUDs) are associated with significant morbidity and mortality that affects individuals and their families. Problems with substance use most often emerge during adolescence and young adulthood. Adolescent-onset SUDs are becoming the most significant public health problem affecting adolescents. Recent work by Merikangas and colleagues showed that 11.4% of adolescents have an SUD, yet only 15.4% of those youths receive treatment. Preventing the onset of an SUD in adolescence remains a critical area of clinical and public health significance.
Familial influence—biological and behavioral
Clinicians and researchers have long observed that SUDs frequently affect multiple members within families over different generations. Researchers have found that approximately 50% of the risk of substance abuse or dependence in adolescence is genetically influenced. The transition between stages of use, from regular use to abuse and dependence is also genetically influenced, although the relative genetic contribution compared with environmental influences varies by substance. Young and colleagues found that a common genetic influence accounts for comorbid substance use during adolescence, specifically problem use of tobacco, alcohol(Drug information on alcohol), and cannabis.
Behavioral modeling of substance use through exposure to parental substance use early in life also accounts for part of the familial association in SUDs. The association between exposure to parental SUDs and the development of an SUD in offspring is consistent with social learning theory. A review by Petraitis and colleagues further described social learning theory as the hypothesis that children model their behavior on people who are important to them and those they frequently interact with, such as their parents. The researchers also reviewed social control theory, which hypothesizes that children who are closely attached to their parents are less likely to break rules because they want to connect with their parents. Children who are closely monitored by their parents and have clear rules are also more likely to conform to their parent’s rules and are less likely to act out by abusing substances.
There is evidence that supports the principles of social learning theory and social control theory. Researchers have examined components of both theories by assessing the relationship between adolescent substance use and parental attitudes toward substances, parental substance use, the quality of the relationship between parent and child, and parental monitoring. Bahr and colleagues found that the family factors that were most strongly associated with an increased prevalence of binge drinking, cigarette use, cannabis use, and illicit drug use were tolerant parental attitudes and sibling substance use. In addition, adolescents who had parents who were tolerant of substance use interacted with higher-risk peers and were more likely to have friends who were substance users.
Exposure to parental substance use increases children’s risk
To understand familial patterns of SUD, family-based research has focused on differentiating between risk mediated primarily by genetics from risk mediated primarily by behavioral modeling through exposure to parental SUD and delineating the risk posed by the combination of both. In a larger longitudinal study of predominantly males with and without ADHD, Biederman and colleagues found an association between exposure to parental SUD and SUD in offspring after controlling for both family history and ADHD.
We recently evaluated a predominantly female sample with and without ADHD. In this study of 552 individuals of whom 71% were female, a specific association was found between exposure to maternal drug use disorders (primarily cannabis) and drug use disorders in female offspring after controlling for family history and ADHD. In other words, mothers who abused drugs increased the likelihood that their daughters would also abuse drugs. Interestingly, research findings have not shown consistent sex patterns when the risk associated with exposure to parental substance abuse was examined. Our finding of a specific risk between mothers and daughters may reflect the greater impact that interpersonal relationships have on an adolescent girl’s risk of using substances relative to the risk in adolescent boys.
It is also important to consider whether the developmental timing of exposure to parental substance use may influence the chances that the child will develop an SUD. For instance, Biederman and colleagues assessed offspring risk of developing an SUD connected with exposure to parental SUD during different developmental stages. Predominantly, boys were at significantly greater risk for developing an SUD when they were exposed to parental SUDs during adolescence than when they were exposed during preschool and latency years.
In our predominantly female sample, we also found that exposure to parental SUD during adolescence was specifically associated with an increased risk of developing an SUD. It is unclear why adolescents are particularly vulnerable to exposure to parental substance use; it may be that behavioral modeling of use at a time when adolescents have greater ease of access to substances partially accounts for their increased risk.