RESUMO
The present study aimed to examine the extent to which the co-occurrence of ADHD and smoking in adolescents could be attributed to common genetic, environmental and psychopathological factors. Data are from an ongoing prospective study of the outcome of early risk factors. At age 15 years, 305 adolescents completed self-report questionnaires measuring tobacco consumption and deviant peer affiliations. Lifetime psychiatric diagnoses were obtained using standardized interviews. DNA was genotyped for the dopamine D4 receptor (DRD4) gene exon III polymorphism. Adolescents with a lifetime diagnosis of ADHD displayed significantly higher smoking activity than non-ADHD controls. A major component of this association could be accounted for by deviant peer affiliations and the comorbidity with oppositional-defiant and conduct disorder, while a minor part was attributable to DRD4 in males but not in females. These findings suggest that the association of ADHD with smoking relies on risk factors shared by the two behaviors.
Assuntos
Envelhecimento/genética , Transtorno do Deficit de Atenção com Hiperatividade/genética , Transtornos Mentais/genética , Receptores de Dopamina D4/genética , Fumar/genética , Adolescente , Adulto , Envelhecimento/metabolismo , Transtorno do Deficit de Atenção com Hiperatividade/metabolismo , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Química Encefálica/genética , Criança , Transtornos do Comportamento Infantil/genética , Transtornos do Comportamento Infantil/metabolismo , Pré-Escolar , Comorbidade , Dopamina/metabolismo , Meio Ambiente , Feminino , Marcadores Genéticos/genética , Predisposição Genética para Doença , Testes Genéticos , Humanos , Lactente , Estudos Longitudinais , Masculino , Transtornos Mentais/metabolismo , Polimorfismo Genético/genética , Estudos Prospectivos , Caracteres Sexuais , Fumar/metabolismo , Fumar/psicologiaRESUMO
Early onset of alcohol and tobacco use during adolescence increases the risk for establishing a substance use disorder in adulthood. Both alcohol and nicotine stimulate the dopamine (DA) and the serotonin (5-HT) systems. The DA system has been implicated in the mediation of the rewarding effects of self-administered drugs of abuse. A possible role of an interaction between these neurotransmitter systems in substance use behavior has been suggested but is as yet unknown. The present study was designed to examine the influence of the DA D4 receptor (DRD4) and the serotonin transporter (5-HTT) genotype and their interaction on adolescent alcohol and tobacco experimentation. Participants were from a longitudinal study of a birth cohort consisting initially of 384 children from a high-risk community sample. At the age of 15 years, adolescents completed a self-report questionnaire measuring tobacco and alcohol consumption. DNA was taken from 305 participants (146 boys, 159 girls) and genotyped for the DRD4 exon III and the 5-HTTLPR polymorphisms. The DRD4 7-repeat allele was associated with greater smoking and drinking involvement in boys. In girls, a significant DRD4 x 5-HTT interaction was detected. Girls without the DRD4 7-repeat allele and who were homozygous for the long allele of 5-HTTLPR displayed the highest smoking and drinking activity. The genetic and potential molecular background underlying adolescent vulnerability to substance abuse is discussed.