Archives of General Psychiatry, 2002, 59(3) : 215-222

This article discusses a study that examined whether the risk factors for juvenile-onset major depressive disorder (MDD) are different from the risk factors for adult-onset MDD. A representative birth cohort was traced prospectively from birth to age 26 years. The participants were part of the Dunedin Multidisciplinary Health and Development Study. Diagnoses of MDD were made according to the "Diagnostic and Statistical Manual of Mental Disorders" (DSM) (1980, 1987, 1994). Risk factors for early childhood covered the period from birth to 9 years. Diagnoses of MDD were made three times prior to adulthood (ages 11, 13, and 15 years) and three times during adulthood (ages 18, 21, and 26 years). Study members comprised four groups as follows: 21 individuals first diagnosed as having MDD in childhood, but not in adulthood; 314 individuals first diagnosed with MDD in adulthood; 34 individuals first diagnosed in childhood whose depression recurred in adulthood by age 26 years; and 629 individuals who had never been depressed. The results showed that the two groups diagnosed with MDD in childhood had similar high-risk profiles in terms of risk factors. The risk factors for depression included parental characteristics, family circumstances, neurodevelopmental characteristics, and child behaviour and temperament. When compared with the adult-depressed group, the factor of caretaker instability, among others, was experienced more by the juvenile-onset groups. The risk profiles for the adult-onset group and never-depressed group were similar, with the exception that the adult-onset group showed elevated childhood sexual abuse. The author concludes that the distinction between juvenile-onset verses adult-onset MDD is important in understanding the diversity that exists within depression. It is suggested that juvenile-onset MDD may be a distinct subtype that is associated with both genetic and psychosocial risk factors in childhood.