Smoking from Adolescence to Adulthood : A 15-year Follow-up of the North Karelia Youth Project

Smoking continues to be the largest single preventable cause of premature mortality and morbidity in Finland as well in other industrialized countries worldwide. Smoking is an addictive behaviour which usually starts in adolescence and has effects on health later in life. Therefore it is important to know the predictors for smoking and ways how to prevent it. The aim of present study was to examine the effects of a smoking prevention program and smoking in general from early adolescence to early adulthood by using longitudinal data. Specifically, the effects of the smoking prevention intervention, predictors of smoking, smoking cessation, and associations of smoking with socioeconomic factors and other health behaviours were assessed. The data was gathered in connection with the North Karelia Youth Project follow-up study during 15 years. A two-year cardiovascular diseases (CVD) risk factor prevention program was carried out among students from grades seven to nine. The subjects of the study were the participants of the North Karelia Youth Project study from six schools in Eastern Finland. At the baseline in 1978 they were 13-year-olds (n=903) and in the last of the six surveys in 1993 28-year-olds. The parents of the subjects were studied twice, in 1978 and 1980. A two-year intervention prevented smoking for several years, and the effect was better among those who were non-smokers at the baseline. The continuity of smoking from adolescence to adulthood was strong: most adolescent smokers were still smoking in adulthood. Moreover, approximately half of the 28-year-old smokers had started smoking after the age of 15. Previous smoking status and smoking by friends were the most important predictors of smoking at the age of 28. Parental and sibling smoking were associated weakly to the smoking of the subjects. One third of all adolescent smokers had stopped smoking before the age of 28, averaging at 2.3 % annual decline. The socioeconomic status of the subject and, especially, education were strongly related to smoking, the lower socioeconomic groups smoking the most. Parental socioeconomic status and intergenerational social mobility were not significantly related to the smoking of the subject in adolescence or adulthood. Smoking was associated positively with the use of alcohol and negatively with physical activity from adolescence to adulthood. The results support the feasibility of a school-based social influence program with a community-based program in smoking prevention among adolescents. Strong continuity of smoking from adolescence to adulthood supports the importance of preventing the onset of smoking in adolescence. It would be useful to continue prevention programs also after the comprehensive school, since so many young start smoking after that. It would likewise be important to develop cessation programs tailor-made for adolescents and young adults. Additionally, the results support the importance of using methods based on social influence in smoking prevention and cessation programs, targeting especially such risk groups as those with low socioeconomic status as well as those with other unhealthy behaviours.