According to a recent study published online in Psychological Science, adolescents who use alcohol or marijuana before the age of 15 are more likely to develop a pattern of substance abuse, obtain criminal convictions, experience academic failure, and obtain sexually transmitted diseases, before the age of 32. Many public health officials have debated whether drug use produces conduct disorder or whether conduct disorder causes drug use; according to Avshalom Caspi, Ph.D., of Duke University, “In fact, drugs are bad for kids…” Dr. Caspi’s long running study in New Zealand observed no history of conduct problems in adolescents who experienced illicit drugs before the age of fifteen; however, this group had the same risk for poor outcomes as those that had a history of conduct disorder. The following is an excerpt of an article from Medpage Today that reviews the study’s findings:
Dr. Caspi and colleagues have been following 1,037 participants in the Dunedin Multidisciplinary Health and Development Study, which enrolled 91% of the children born between April 1972 and March 1973 in Dunedin, New Zealand.
The children were enrolled at age three and follow-up assessments were conducted when the cohort members were five, seven, nine, 11, 13, 15, 18, 21, 26, and 32. Almost all of the living study members (96%) took part in the assessment at age 32.
“We have history about these children from their birth,” Dr. Caspi said, “so we knowing an enormous amount about these kids up to the point they started using drugs” — mainly alcohol and cannabis.
That detailed information was combined with a statistical method called propensity matching — used to overcome the lack of randomization — to evaluate the risk of five negative outcomes at age 32: having a substance dependency, failing to finish school, acquiring herpes simplex, having a criminal conviction, and, in the case of females, being pregnant before the age of 21.
The researchers found that 17% of adolescents with a history of conduct problems were early drug users, compared with 9.1% of those with no such history. The odds ratio was 2.1, with a 95% confidence interval from 1.4 to 3.1.
On the other hand, 56 of the 114 early-exposed adolescents had no history of conduct problems.