A sum of ten items was used to assess impulsivity at baseline (age 18) and subsequently at ages 25, 29, and 35, respectively. Six of these items (e.g., I often follow my instincts, hunches, or intuition without thinking through all the details) were drawn from the short-form of the Tridimensional Personality Questionnaire (Short-TPQ; Sher et al., 1995) and the remaining four items (e.g., I often do things on the spur of the moment) were taken from the Eysenck Personality Inventory (EPI; Eysenck and Eysenck, 1968). Internal consistency, as measured by coefficient alpha (α), was 0.79 at age 18, 0.81 at age 25, 0.75 at age 29, and 0.75 at age 35 for the impulsivity scale.
