Clustering behaviours among 13-year-old Portuguese adolescents

Aim: The aims of this study were to identify clustering of behaviours in young adolescents and to analyse differences in food intake according to clusters. Subject and methods: A cross-sectional study was carried out on adolescents’ behaviours comprising 2,160 adolescents aged 13 years attending schools of Porto, Portugal. We used data of 875 girls and 737 boys with complete information for all variables considered in the cluster definition (tobacco and alcohol use, sport activities, fruit intake, daily sleep hours). The average method was used to find the natural structure of clusters. Results: We identified three clusters: cluster 1 characterized by never smokers and never drinkers represented those with higher intake of fruits and lower intake of soft drinks. Cluster 2 comprised essentially tobacco and alcohol experimenters and was almost similar to cluster 1 regarding the other characteristics. Cluster 3 represented mostly regular smokers and drinkers, and those with the lowest daily sport activities, the lowest number of daily sleep hours, the lowest mean of fruit consumption and the highest intake of sweets and soft drinks. Conclusion: Our findings show that even in the early stages of adolescence there is a cluster of smoking, alcohol use and food intake, providing further evidence of the clustering of unhealthy behaviours