Photo by Ambika Singh

Adolescence is a time of sturm und drang, storm and stress. That’s both a cliché and the plot of every coming-of-age story. But why? For sure, as children grow into adolescence, they begin shouldering more responsibilities and navigating new terrain—from high-stakes tests to driving lessons to complicated interpersonal relationships. But are these challenges alone enough to trigger adolescents’ hard-to-tame emotions, or is something else going on?

Russell Romeo, a Tow associate professor in Barnard’s psychology and neuroscience and behavior programs, studies adolescents and stress—and demonstrates that teens have to contend not only with pressures we’re all aware of but also with a developing brain that responds to stress in different ways than do the brains of children and adults. “It’s a perfect storm that may be one of the contributors to why we see so many stress-related disorders during adolescence,” Romeo says.

Surprisingly, Romeo has been able to understand teenagers’ experiences with stress by looking at responses to stress in mice and rats, both of which process it in ways remarkably similar to humans.

In both humans and rodents, tensions created by difficult situations cause a series of neurons to fire, triggering a cascade of hormones—including cortisol in humans and corticosterone in rodents. These hormones can free up stores of energy and jump-start immune responses. But prolonged exposure to them damages the metabolism, immune system, and cognitive functioning. “When you are chronically engaging this system,” Romeo explains, “you have a problem.”

His research has found that adolescent rodents respond intensely to stressors and take two to three times as long to return to their hormonal baseline as adults. These responses, in turn, seem to affect adolescent rodent behavior. In one test, researchers place mice in a large, open box. Mice that have previously been exposed to stress (for example, by being restrained for a period of time) are less likely to explore. “Mice are naturally curious animals,” Romeo says. “But if they are showing signs of stress, they will typically stay against the walls.” His experiments have shown that stressed adolescent mice “take longer to reach the center of the box and spend less time there overall” than adults do, with effects especially pronounced in females. Romeo has found they show a higher hormonal response to stress than males.

Over time, prolonged exposure to stress-related hormones during adolescence can have lasting effects on areas of the rodent brain still under development—including the prefrontal cortex, which is associated with executive function, impulse control, and working memory. “Cells become smaller, and the elaborate branches of neural cells called dendrites shrink and become less complex,” Romeo explains.

The consequences are dramatic. Romeo’s lab has found that exposure to stress during adolescence dramatically decreases play among his lab animals. Other laboratories have shown that impulse control decreases as well.

Can we translate the behavior of rats and mice into human emotion and activity? Romeo says perhaps so. He speculates that the effects of stress on adolescent rodent brains may shed light on why some human teenagers develop problems such as anxiety, depression, and drug abuse.

What’s less clear is whether these changes are permanent or can be reversed over time through stress reduction. “We are still trying to figure out if stress leaves an indelible mark on our nervous system,” says Romeo.

A mentor in the Summer Research Institute, a ten-week program for Barnard students who work closely with faculty in their labs, Romeo has recently begun to develop with his students a new line of research: exploring whether exposure to stress in adolescence correlates with metabolic dysfunctions such as obesity and diabetes. Romeo hopes that his research into the mechanisms by which stress affects adolescent brains might aid doctors and better assist teenagers under stress, either through pharmaceutical interventions or through methods such as diet, exercise, or mental exercises.

While the stress of teenage years isn’t going away any time soon, Romeo’s research might one day help adolescents—and the adults in their lives—manage it better. •

 

Michael Blanding is a freelance writer and author of The Map Thief.

neuroscience
psychology
STEM