Oct. 18, 2007 -- Scientists have a new clue about why some people are resilient while others fold in the face of stress.
New research links resilience to a brain chemical called BDNF -- at least, in mice.
If that proves true in people, it might be possible to create drugs that lower BDNF and boost resilience, scientists suggest in tomorrow's edition of Cell.
The resilience researchers included Vaishnav Krishnan, an MD-PhD student in the psychiatry and neuroscience departments of the University of Texas Southwestern Medical Center in Dallas.
They studied normal-sized male mice that spent 10 minutes per day for 10 days visiting the cage of big, mean mice.
After those not-so-friendly visits, all of the normal-sized mice acted anxious. But some of the mice got over it, while others didn't.
The vulnerable mice lost weight, lost interest in sugary water, avoided other mice, and had shifts in their body temperature's fluctuations.
The resilient mice didn’t have those problems. They had lower levels of BDNF in certain brain regions, compared with the vulnerable mice.
It's not that BDNF is bad.
The brain chemical might help animals learn to avoid bad situations, notes Eric Nestler, MD, PhD, who heads the lab where Krishnan works.
"But under conditions of extreme social stress, susceptible animals may be 'overlearning' this principle and generalizing it to other situations," Nestler says in a news release.
"They avoid their aggressors, but they also avoid all mice and even other fun things like sugar or sex," says Nestler.
What about people? The scientists measured BDNF in brain tissue from autopsies done on men who had or hadn't been depressed.
The depressed men had higher BDNF levels than men who hadn't been depressed. The findings probably weren't due to antidepressant use, according to the study.
It will take more work to see if it's possible to lower BDNF and raise resilience without causing other problems.
The researchers aren't suggesting that resilience is only about BDNF. Other factors also affect how people react to stress and setbacks.