After harmonizing all item data on neuroticism from multiple instruments, comparable neuroticism scores were obtained for all cohorts.36 These scores were estimated for all participants after conducting IRT analysis on the available item data for neuroticism from the NEO Personality Inventory, Eysenck Personality Questionnaire, and the International Personality Item Pool inventory, all item data for harm avoidance from the Cloninger’s Tridimensional Personality Questionnaire, and all item data for negative emotionality from the Multidimensional Personality Questionnaire (see eMaterials and methods). For the Generation Scotland cohort phenotypes were summed scores on the neuroticism scale of the EPQ Revised Short Form.
