Early childhood risk factors differentiated juvenile onset from adult onset major depressive disorder.

Assessment of risk factors Childhood risk factors were assessed up to 9 years of age: neurodevelopmental characteristics (perinatal insults, gross motor skills, and intelligence quotient); parental characteristics (mother’s internalising symptoms, including depression and anxiety, mother–child interactions, criminal conviction history, and parental disagreement about discipline); family characteristics (number of residence changes, socioeconomic status, unwanted sexual contact, and loss of a parent); and child behaviour and temperament (inhibited or undercontrolled temperament, peer problems, and depressive symptoms).