Kids who experience neglect have previously been found to be more prone to a behavior known as "indiscriminate friendliness," characterized by an inappropriate willingness to approach adults, including strangers. Now, UCLA researchers are reporting that this behavior is rooted in brain adaptations associated with early-life experiences.
The UCLA group used brain imaging to demonstrate that youths who experienced early maternal deprivation - specifically, time in an institution such as an orphanage prior to being adopted - show similar responses to their adoptive mother and to strangers in a brain structure called the amygdala; for children never raised in an institutional setting, the amygdala is 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," said Aviva Olsavsky, the study's first author. "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."
Indiscriminate friendliness is in some sense a misnomer. The behavior is not characterized by a deep friendliness, Olsavsky explains, but simply by a lack of reticence that most young children show toward strangers.
The UCLA researchers found that while the typically raised children exhibited higher amygdala signals for their mothers relative to strangers, the previously institutionalized youths showed amygdala responses to strangers that were similar to those they showed toward their adoptive mothers. Additionally, the children with a history of institutional rearing showed greater amygdala reactivity to strangers than did the typically raised children. Reduced amygdala differentiation was correlated with greater reports of indiscriminate friendliness by the parents.
In order to understand the heterogeneity of the sample, the researchers examined the role of 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.
"This can be a very frightening behavior for parents," said UCLA's Nim Tottenham, the study's senior author. "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."
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Source: University of California - Los Angeles