Adopted children, regardless of age, are all susceptible to different levels of attachment issues. The serious cases of attachment problems include an infant's failure to thrive, which evolves from being neglected or malnourished. Older child adoptions have more complicated origins but when they affect the family dynamic can sometimes lead to what is called a disrupted adoption.
Foster children are far more likely to experience problems with attachment. If a child has had a lot of issues in the past with bonding, they may have a reactive or other kind of attachment disorder. There is some disagreement about the conditions of attachment disorders, but it's usually agreed that a child with RAD or AD did not develop an ability to trust his or her caregivers. Sometimes this trust is based on basic needs, such as food, but other times the disorder develops from emotional neglect.
According to the Mayo Clinic website, babies with RAD do not respond to peekaboo or other forms of playing and may not respond to someone trying to get its attention. For older children and adolescents, RAD may come in the form of being standoffish or overly aggressive, and inability to ask for support or assistance, or dismissing comments and gestures intended to comfort the child. Children with RAD are also more likely to abuse drugs and alcohol during their adolescence.
As a child matures, the disorder either makes them extreme extroverts or introverts. These children may need to speak with a counselor and infants who are disinterested in their caregivers should be taken to a doctor for a psych evaluation.