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CHICAGO - One socially crushing moment - think schoolyard bullies - can challenge the survival of new nerve cells in the brain and may even lead to depression, US researchers say.
In a study of young rats threatened by aggressive older rats, the bullied ones were able to generate new nerve cells in key memory and emotion regions of the brain but most of those cells later died.
The research suggests that stress kills young nerve cells, a finding that might lead to potential interventions.
"If we can keep these new nerve cells alive, we might be able to forestall or prevent the types of depressive symptoms that might normally occur," said researcher Daniel Peterson, of Rosalind Franklin University of Medicine and Science in Chicago.
Dr Peterson's team put a young rat in a cage with two older rats for 20 minutes. The older rats quickly cornered, pinned down and often bit the younger one.
The younger rats became fearful and depressed around the bigger animals, with their stress hormones six times higher than young rats who were spared the stressful encounter.
Dr Peterson and his colleagues had expected that elevated stress hormone levels would prevent the development of young nerve cells or kill them off immediately.
Instead, when the rats' brains were examined, the researchers found new cells had developed but that only about a third of them had survived a week later.
"There is this time frame after you encounter this dreadful stress episode where you could probably intervene," Dr Peterson said.
He plans to examine what role antidepressants might play in rescuing nerve cells.
But because most antidepressants need weeks to take effect, he believes that may not be quick enough to do any good.
- REUTERS
