The NDIT (Nicotine Dependence in Teens) Study is a prospective cohort investigation of 1294 students recruited in 1999 from all grade 7 classes in 10 secondary schools in Montreal. Its main objective is to describe the development of symptoms of nicotine dependence (ND) in relation to cigarette smoking in adolescents, and to identify genetic, socio-demographic, psychosocial, and environmental risk factors for the onset of cigarette use and ND symptoms.
Schools for the NDIT Study were hand-picked in consultation with schools boards and school principals to assure a mix of students according to socioeconomic status (high, moderate, low), language (French, English), and place of residence (urban, suburban, rural).
Participants completed 45-minute, self-report questionnaires every 3-4 months over 5 years during secondary school (for a total of 20 questionnaires per student). The questionnaires collected detailed data on each participant's experience with cigarette smoking, as well as with the onset and experience of symptoms of nicotine dependence among those who had smoked. Also, to permit studies of other risk factors for cancer and cardiovascular disease, self-report data were collected on physical activity, sedentary behaviors, diet, and use of alcohol, and we measured height, weight, skinfold thickness, waist circumference, and blood pressure biannually. Blood samples and saliva samples were collected from participants in order to extract DNA and investigate genes that relate to smoking. All participants and a parent or guardian provided written informed consent.
Questionnaires were also completed after graduation from high school in 2007–08 and 2011–12 (survey cycles 21 and 22, respectively) when participants were aged 20 and 24 years on average, respectively.
Participants in the NDIT Study have now graduated from secondary school and have moved on to the job market, CEGEP or university. Over the next 4 years, from 2015 to 2019, data will be collected on their experiences with cigarette smoking as young adults. This phase of the study will permit more in-depth understanding of late onset smoking and of cessation, as these young people take on new roles and responsibilities in the work force, as spouses, and as young parents.
NDIT has been supported financially by the Canadian Cancer Society (CCS) since its inception in 1999. It was funded initially for 3 years and to date has received three renewals - one in 2002-05, one in 2006-13, and the other in 2015-19. The NDIT team is deeply grateful to the CCS for their continuing support of the NDIT Study.