what are some of the symptoms?
Infants up to about 18–24 months "may" present with non-organic failure to thrive and display abnormal responsiveness to stimuli. The core feature is severely inappropriate social relating by affected children.
Reactive attachment disorder
 Infants up to about 18–24 months "may" present with non-organic failure to thrive and display abnormal responsiveness to stimuli. Laboratory investigations will be unremarkable barring possible findings consistent with malnutrition or dehydration, while serum growth hormone levels will be normal or elevated.

The core feature is severely inappropriate social relating by affected children. 
what is reactive attachment disorder? It is a severe and relatively uncommon disorder that can affect children. what causes it? It is based on a problematic history of care and social relationships. can it be diagnosed? It can olny be diagnosed by a psychiatrist and any assessment must include a comprehensive evaluation of the child's individual and family history.
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Reactive attachment disorder [SEP] Signs and symptoms
Pediatricians are often the first health professionals to assess and raise suspicions of RAD in children with the disorder. The initial presentation varies according to the child's developmental and chronological age, although it always involves a disturbance in social interaction. Infants up to about 18–24 months "may" present with non-organic failure to thrive and display abnormal responsiveness to stimuli. Laboratory investigations will be unremarkable barring possible findings consistent with malnutrition or dehydration, while serum growth hormone levels will be normal or elevated. The core feature is severely inappropriate social relating by affected children. This can manifest itself in three ways: While RAD occurs in relation to neglectful and abusive treatment, automatic diagnoses on this basis alone cannot be made, as children can form stable attachments and social relationships despite marked abuse and neglect.