Cohort profile: risk patterns and processes for psychopathology emerging during adolescence: the ROOTS project

Mental illness makes a major contribution to the global burden of disease. The impact of disorders such as depression and anxiety has been heightened by the increasing success of public health measures in controlling physical diseases. Mental health disorders are severely impairing in their own right but may also exacerbate the disability resulting from physical disease. The situation will be worse globally as the pattern of morbidity seen in the developed world sweeps over low- and middle-income countries. Mental illness is commonly understood to result from complex interactions between vulnerability and stress, though such a model is uniquely difficult to study, particularly in longitudinal or life course designs. A considerable proportion of individuals who experience mental illness during their lives report the emergence of symptoms and impairment during the adolescent years.