Psychosocial characteristics of adolescent smokers before they started smoking: evidence of self-selection. A prospective study.

Evidence of noncomparability of self-formed smoker and nonsmoker groups of adolescents from the Child Health and Development Studies of the University of California, Berkeley, was found in a study of antecedent psychosocial characteristics (observed at age 10) before the adoption of the smoking habit. With possible confounding factors controlled, eventual smokers showed significantly greater prevalence than nonsmokers of Type A personality traits, extraversion, psychoticism, anger, and restless sleep. Eventual smokers were lower in socioeconomic status than nonsmokers, and also exhibited significantly lower mean scores for the Raven Progressive Matrices and Peabody Picture Vocabulary tests. For each trait, the trends of the data were consistent in boys and girls. Since many of these traits are shown to "track" into adult life, where they are then related to coronary heart disease, the role of self-selection requires further consideration in causal inferences about smoking and coronary heart disease.