The association between cigarette smoking and psychiatric disorders is well established for adult populations. However, only limited number of studies has investigated whether the young onset age of daily smoking (DS) among adolescents is associated with psychiatric morbidity and vice versa.

Data from 508 adolescents admitted to psychiatric hospitalization were collected. Cox proportional hazard model were used to compare the initiation of DS between adolescents with and without substance use (SUD), and other psychiatric disorders.

Rates of DS were high in each diagnostic category. Boys started smoking at younger age (mean 12.4 years) than girls (13.0 years). Both boys and girls diagnosed with conduct or oppositional defiant disorders (COD) and also girls with SUD started daily smoking earlier as compared to those of same gender without these disorders.COD were found to be primary to the initiation of DS among boys. SUD, psychotic, and depressive disorders (DEP) were found to be secondary to DS among both genders.

DS in adolescence is related with later SUD. COD are associated with subsequent initiation of DS among boys. The temporal gap between smoking initiation and COD is shorter among girls. Gender difference plays a role in association of DS and DEP. Initiation of DS at very early age should alert health care professionals of development of later psychopathology, especially SUD.