Abstract
This paper describes the history of the concept of infant depression, which has been at the beginning of the discipline of infant mental health, and reviews classification and diagnosis issues, along with some animal models. Several diagnostic criteria have yielded different prevalence rates, and some being unrealistic, but we still do not know when infant depression begins, what its outcome is, and what are its different aspects. It is suggested that infant depression needs a certain amount of emotional and cognitive development to unfold, and that it might not exist before 18β24 months of age, a crossover during which major autoreflexive, cognitive, and emotional abilities emerge. Depression could be an outcome of attachment disorganization in infancy, as depression and disorganization seem to share the same learned helpnessness psychopathological process. Developmental psychopathology considers trouble more from a dimensional point of view rather than from a categorical one, and more as the result of several factors with a sequential action rather than the effect of a genetic disorder with direct expression. Before the limit of 18β24 months, the concept of relational withdrawal seems more applicable and useful.