LOS ANGELES — Perhaps not surprisingly, sixth graders who demonstrated an aggressive temperament and/or symptoms of depression were more likely than their peers to begin using alcohol and other drugs by eighth grade, in a longitudinal study performed by researchers at the University of Washington, Seattle.
It was the third independent risk factor researchers detected—an early onset of puberty—that was less predictable, and it might serve as an early red flag for physicians.
Dr. Carolyn A. McCarty and her associates in the university's departments of pediatrics and psychology recruited 521 sixth graders from four public schools in the Seattle area, interviewing them every 6 months for 2.5 years, until they entered the eighth grade.
Children with conduct problems in school and/or depressive symptoms on a psychological instrument were oversampled in the survey supported by grants from the National Institute of Mental Health. At the study's onset, just 5.4% of sixth graders were using any substance, the most common being alcohol at 4.2%. By the study's conclusion, 16.7% of the teens—who had now reached eighth grade—reported using alcohol (13.2%), tobacco (4.2%), marijuana (6.8%), and/or other illicit substances (1.5%).
Sex, race, frustrated temperament, and externalizing symptoms were not significantly, independently associated with initiation of substance use over the course of the study, but several factors were, after adjustment for other variables. Most pronounced were aggressive temperament (hazard ratio, 1.61), pubertal status (HR, 1.42), and depressive symptoms, (HR, 1.04).
The link to early puberty (by sixth grade) “doesn't seem to be a blip,” since it is consistent with previous research that only examined initiation of alcohol use, said Dr. McCarty, a psychologist who has a dual appointment in pediatrics and psychology at the university.
The reason for the apparent link is still unclear, but several theories have been proposed, she said in an interview at the annual meeting of the Society for Adolescent Medicine, where the study was presented in poster form. “Some of the literature suggests that kids who go through puberty early associate with more deviant peers. It could also be that biologically, morphologically, they look older, so people treat them as if they're older. People might be more willing to offer them substances that they wouldn't [offer] to someone who looks younger.”
Dr. McCarty suggested that pediatricians, family physicians, ob.gyns., and endocrinologists take note when a girl or boy enters puberty early (by sixth grade), or shows signs of aggression and/or depression. “I would recommend doing a more thorough risk assessment of behavior so that they can know whether [alcohol and/or substance use] may or may not be an issue for a particular child.” In the case of early puberty, physicians need to consider possible behavioral implications of the physiological change. “Are they feeling older than their peers? And what does that mean for them?” she said.