Transtorno de apego reativo is characterised by grossly abnormal attachment behaviours in early childhood, occurring in the context of a history of grossly inadequate child care (e.g., grave neglect, maltreatment, institutional deprivation). Even when an adequate primary caregiver is newly available, the child does not turn to the primary caregiver for comfort, support and nurture, rarely displays security-seeking behaviours towards any adult, and does not respond when comfort is offered. Transtorno de apego reativo can only be diagnosed in children, and features of the transtorno develop within the first 5 years of life. However, the transtorno cannot be diagnosed before the age of 1 year (or a developmental age of less than 9 months), when the capacity for selective attachments may not be fully developed, or in the context of Transtorno do espectro autista.