Intermittent placement and non-attachment can result in mental illness.
Delay, Despair, and Detachment: The Physical and Mental Health of Foster Children
Reactive Attachment Disorder: “Markedly disturbed and developmentally inappropriate social relatedness in most contexts, beginning before age five years, as evidenced by either (1) or (2):
(1) persistent failure to initiate or respond in a developmentally appropriate fashion to most social interactions. As manifest by excessively inhibited, hypervigilant, or highly ambivalent and contradictory responses (e.g. the child may respond to caregivers with a mixture of approach, avoidance, and resistance to comforting or may exhibit frozen watchfulness.)
(2) diffuse attachments as manifest by indiscriminate sociability with marked inability to exhibit appropriate selective attachments (e.g. excessive familiarity with relative strangers or lack of selectivity in choice of attachment figures.)
The DSM-IV indicates that Reactive Attachment Disorder (RAD) may arises from the “repeated changes of primary caregiver that prevent formation of stable attachments (e.g. frequent change in foster care.)” Interestingly, RAD is the only relational diagnosis in the DSM-IV. All the other psychiatric diagnoses involve a single person: the patient.