Early-onset depressive disorders predict the use of addictive substances in adolescence: a prospective study of adolescent Finnish twins.
OBJECTIVE
To explore the developmental relationships between early-onset depressive disorders and later use of addictive substances.


METHODS
A sample of 1545 adolescent twins was drawn from a prospective, longitudinal study of Finnish adolescent twins with baseline assessments at age 14 years and follow-up at age 17.5 years.


METHODS
At baseline, DSM-IV diagnoses were assessed with a professionally administered adolescent version of Semi-Structured Assessment for Genetics of Alcoholism (C-SSAGA-A). At follow-up, substance use outcomes were assessed via self-reported questionnaire.


RESULTS
Early-onset depressive disorders predicted daily smoking [odds ratio (OR) 2.29, 95% confidence interval (CI) 1.49-3.50, P < 0.001], smokeless tobacco use (OR = 2.00, 95% CI 1.32-3.04, P = 0.001), frequent illicit drug use (OR = 4.71, 95% CI 1.95-11.37, P = 0.001), frequent alcohol use (OR = 2.02, 95% CI 1.04-3.92, P = 0.037) and recurrent intoxication (OR = 1.83, 95% CI 1.18-2.85, P = 0.007) 3 years later. ORs remained significant after adjustment for comorbidity and exclusion of baseline users. In within-family analysis of depression-discordant co-twins (analyses that control for shared genetic and familial background factors), early-onset depressive disorders at age 14 predicted significantly frequent use of smokeless tobacco and alcohol at age 17.5.


CONCLUSIONS
Our results suggest important predictive associations between early-onset depressive disorders and addictive substance use, and these associations appear to be independent of shared familial influences.
Sihvola
Elina
E
Department of Public Health, University of Helsinki, Finland. elina.sihvola@helsinki.fi
Rose
Richard J
RJ
Dick
Danielle M
DM
Pulkkinen
Lea
L
Marttunen
Mauri
M
Kaprio
Jaakko
J
D000293:Adolescent; D017668:Age of Onset; D003866:Depressive Disorder / Q000453:epidemiology / Q000523:psychology*; D004200:Diseases in Twins / Q000453:epidemiology / Q000523:psychology*; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D019966:Substance-Related Disorders / Q000453:epidemiology / Q000209:etiology*