PITT, OHSU: When early life stress occurs determines its im...( uring early childhood. To simulat...),Health

To simulate significant early-life stress in humans, the scientists separated nine infant monkeys from their mothers during the first week of life and placed them in social groups of three to four other monkeys. The social groups consisted of males and females ranging in ages, similar to groups formed in the wild. The researchers then introduced experienced mothers, often referred to as super moms, when the infant monkeys were one to three months of age. These adoptive mothers were paired with the infant monkeys as a form of corrective therapy. The timing of the introduction of these super moms was varied because the scientists wanted to determine the optimal timing for initiation of therapies to counteract the impacts of the early-life stress.

After being paired with the super moms, we then observed the baby monkeys throughout their first year of life, explained Cameron. As a control group for comparison, we observed the behavior of monkeys that lived with their natural mothers as well as a social group for the first six months of life. At six months the control monkeys had their mothers removed from the social group. Six months is the typical age when juvenile monkeys begin to gain independence from their mothers in the wild.

The scientists noted that the infants separated from their mothers at one week of age displayed a series of atypical behaviors. Specifically, these animals spent significantly more time alone than animals in the control group and limited their social contact. They also developed self-comforting behaviors, such as thumb or toe sucking. However, when separated monkeys were paired with an adoptive mother within the first month, all of these behaviors were rapidly reversed. For monkeys paired with adoptive mothers in the second month of life, the reversal took place, but at a slower pace. Monkeys paired in the third month of life did not exhibit a reversal of these atypical behaviors.

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24-Oct-2004