The question of what lures a person toward drug addiction and abuse is difficult to answer. However, University of Pennsylvania researchers have confirmed that a mixture of both genetic and environmental forces play a role.

According to the researchers, their study, which involved adopted children and their families, confirms “drug abuse is etiologically complex with important genetic and shared-environmental influences. Both the genetic and the familial environmental influences on drug abuse are themselves multi-faceted.”

The researchers assessed a Swedish cohort of 18,115 adopted children for the study, in which there were records available both for the biological and adoptive relatives. They also assessed 78,079 biological parents and siblings as well as 51,208 adoptive parents and siblings.

Their findings revealed that the risk for drug abuse was significantly higher in children whose biological parents abused drugs. In terms of the “nature” aspect of drug abuse, the researchers found that the risk of drug abuse was higher among the adoptive siblings of adopted children with drug abuse. There was also a trend toward an increased risk of drug abuse in adopted children if their adoptive parents had abused drugs, but it was not found to be significant.

The authors wrote that the results suggest that social influences, such as the actions of peers or the availability of drugs, “are more potent environmental risks for drug abuse than direct psychological transmission of drug abuse from parent to child.”

They found that in regression analyses, both a genetic risk index and an environmental risk index strongly predicted the risk of drug addiction:

“The genetic risk index included a history of drug abuse, criminal activity, and psychiatric or alcohol problems in a biological relative; the environmental risk index included a history of divorce, death, criminal activity, and alcohol problems in adoptive parents, as well as a history of drug abuse and psychiatric or alcohol problems among adopted siblings. Additional models also revealed a significant, positive interaction between the genetic and environmental risk indices. Specifically, the impact of an adverse environment on the risk of drug abuse was far greater in children with a high genetic susceptibility to drug abuse, the researchers wrote.”

According to the authors, “Adverse environmental effects on drug abuse are more pathogenic in individuals with high levels of genetic risk.”

They conclude that drug abuse “is an etiologically complex syndrome strongly influenced by a diverse set of genetic risk factors … by a vulnerability to other externalizing disorders, and by a range of environmental factors.”

Source: Medpage Today

Heather Rudow is a staff writer for Counseling Today. Email her at hrudow@counseling.org.

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