The researchers then compared the loss of synaptophysin in rats that were stressed during adolescence with rats that experienced significant stress during ages comparable to childhood. The stressor used for this age group was repeated maternal separation (RMS). The scientists found no significant difference in synaptic density between rats that had social stress during adolescence or rats that had early RMS. However, the density of synapses in the hippocampus of both groups was reduced significantly when compared with control rats.
These findings are the first to demonstrate that exposure to a significant stress during adolescence can have enduring consequences on the connections formed in the hippocampus in adulthood. These data may suggest why early traumatic stress, such as physical or sexual abuse or neglect, is associated with a decrease in the size of the hippocampus in adulthood.
"These preclinical data suggest that stress experienced early in life alters the normal developmental trajectory of the hippocampus, but that these changes are not apparent until later in life," says Andersen.
In another study, non-smoking adolescents with attention deficit hyperactivity disorder (ADHD) showed significant improvement in their ability to inhibit a motor response following acute nicotine administration. Nicotine produced a short-term improvement that was as large as the improvement seen after giving them Ritalin, the standard drug used to treat ADHD, says Alexandra Potter, PhD, of the University of Vermont in Burlington.
"This is the first study we kn
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Contact: Dawn McCoy
dawn@sfn.org
202-462-6688
Society for Neuroscience
8-Nov-2003