UCLA researchers note that children who are profoundly neglected have been found to be more prone to a behavior known as “indiscriminate friendliness,” which is characterized by an inappropriate willingness to approach adults, including strangers. They conducted a study that found for the first time that the underlying cause for this behavior is brain adaptations associated with early-life experiences. They reported their findings on December 1 issue of the peer-reviewed journal Biological Psychiatry.
The study group comprised 67 individuals between the ages of 4 and 17. Approximately half the children had spent time in institutions, ranging from five months to about five-and-a-half years, before being adopted. Using an imaging technology known as functional magnetic resonance imaging (fMRI), the investigators found that children who experienced early maternal deprivation (i.e., time in an institution such as an orphanage prior to being adopted) exhibited similar responses to their adoptive mother and to strangers in a brain structure called the amygdala. Among children who were never placed in an institutional setting, the amygdala was far more active in response to the adoptive mother. This reduced amygdala discrimination in the brain correlated with parental reports of indiscriminate friendliness. The longer the child spent in an institution before being adopted, the greater the effects.
“The early relationship between children and their parents or primary caregivers has implications for their social interaction later in life, and we believe the amygdala is involved in this process,” explained first author Aviva Olsavsky, a resident physician in psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA. She added, “Our findings suggest that even for children who have formed attachments to their adoptive parents, this early period of deprivation has led to changes in the brain that were likely adaptations and that may persist over time.”
The researchers note that indiscriminate friendliness is in some sense a misnomer because the behavior is not characterized by a deep friendliness; rather it is simply a lack of restraint that most young children show toward strangers. “This can be a very frightening behavior for parents,” explained senior author Nim Tottenham, an associate professor of psychology at UCLA. He added, “The stranger anxiety or wariness that young children typically show is a sign that they understand their parents are very special people who are their source of security. That early emotional attachment serves as a bedrock for many of the developmental processes that follow.”
The amygdala is located in the limbic system of the brain; it is involved in a variety of functions, including detecting the relative importance of stimuli, and is believed to play an important role in intense relationships and attachments. Rodent studies have found that the process of forming a maternal bond early in life has powerful effects on amygdala development and attachment-related behaviors. Other studies have shown that children whose early childhood did not include the typical caregiving experience may exhibit a variety of behaviors, including indiscriminate friendliness; however, such behavior had not been well characterized at the brain level.
The study participants underwent fMRI while they were shown pictures of their adoptive mother and of an unfamiliar female. As part of the study, the parents of the participating children were given a questionnaire designed to gauge the probability of their child wandering away with a stranger, as well as how trusting the child was with new adults. The investigators found that the typically raised children exhibited higher amygdala signals for their mothers relative to strangers; however, the previously institutionalized children showed amygdala responses to strangers that were similar to those they showed toward their adoptive mothers. Furthermore, the children with a history of institutional rearing showed greater amygdala reactivity to strangers than did the typically raised children. Reduced amygdala differentiation correlated with increased reporting of indiscriminate friendliness by the parents.
The researchers also looked at impact from the age at adoption. They found that children who had been adopted later displayed the least discrimination on the scans and the greatest degree of indiscriminate behavior. The authors note that their study raised two questions: (1) What, if any, effects does early maternal deprivation has on children as they move into adulthood? (2) Do these findings also apply to less severe forms of deprivation, such as neglectful home environments?
The researchers are continuing to use fMRI to examine parental role in brain development and the contribution of early experiences to mental health outcomes later in life. The study was part of a larger grant study, funded by the National Institute of Mental Health, examining brain development in children with a history of institutional caregiving.