Structure does not influence family function during adolescence. However, the adolescent perception of the family structure influences social support, the consumption of drugs and alcohol and the presence of depressive symptoms.

In the last 8 years the consumption of toxic substances among adolescents has dropped, mainly because of less alcohol consumption. However, new forms of consumption of alcohol and other illegal drugs, especially at weekends, emerged and daily consumption of tobacco increased.

This study provides useful data on motivation that could be used to improve smoking prevention interventions among adolescents. The most important factors seem to be peer influence, parental attitudes, easy access to tobacco and symptoms of dependence.

The consumption of tobacco among adolescents is related to family function and having friends who smoke. The low dependency and the motivation to change make this stage of life a good moment to concentrate on anti-smoking counselling.