Hayward et al. (2000) studied the predictors of panic attacks in adolescents, and hypothesized that predictors would include negative affectivity (emotionality characterized by fear, sadness, self-dissatisfaction, hostility, and worry), female sex, anxiety sensitivity (the tendency to respond fearfully to anxiety symptoms), and childhood separation anxiety disorder. The study included 2,365 adolescents, with an average age of 15.4 at study entry, and the sample was multiracial. The prospective study lasted for 3 years; participants were assessed annually (a total of 4 times), using questionnaires and interviews. The authors found that negative affectivity was a predictor of the onset of panic attacks, and it was also a predictor of the onset of depression. Furthermore, there is a great deal of overlap in depression and panic attacks. Anxiety sensitivity was a unique predictor of panic attacks. Thus, the study highlights the comorbidity of depression and panic, and shows that anxiety sensitivity is a good predictor of the onset of a panic attack.