It's a recurring subplot in teen movies from "The Breakfast Club" to the Pittsburgh-set "The Perks of Being a Wallflower." It has been a theme with teenage characters in HBO's "The Sopranos" and Showtime's "Homeland."
And it's no wonder. Episodes of depression can be just as common in teens as in adults.
"As many as one in five teenagers will have an episode of depression by the end of adolescence," said Jennifer Silk, a psychiatric researcher at the University of Pittsburgh, "and most people who are depressed as adults had their first onset between the ages of 13 and 20."
She and others at Pitt are trying to find out what makes some young people more vulnerable to depression, and to come up with new ways of intervening early, in hopes of preventing them from being lifelong sufferers.
The problems for some youngsters start before their teen years, when they experience extreme anxiety over social situations, whether it's attending school or being invited to a party. Before puberty, the numbers of boys and girls experiencing this social anxiety are about equal, she said, but once puberty kicks in, the anxiety often segues into depression, and it hits twice as many girls as boys, a ratio that persists throughout the lifespan.
The anxiety and depression may be two different reactions to the same fear -- being rejected by peers. Most teens are "pretty concerned about people thinking negatively about them," the Pitt researcher said, but in depression, "it's exacerbated."
In girls particularly, the surge of sex hormones that comes with puberty may set the stage for depression, particularly if they are already vulnerable to it.
"I definitely believe the kids who go on to become depressed are genetically vulnerable," she said. "It seems the genetic vulnerability for anxiety and depression go together. That probably leads to increased brain reactivity to threat."
The environment they grow up in also plays a part, she said. "If these vulnerable kids feel very accepted and more secure either because their parents did a really good job or they happen to have a good set of friends, they'll probably be OK. But the combination of genetic vulnerability and having negative experiences with peers probably increases the likelihood they'll go on that trajectory and become depressed."
One reason boys may be less likely to become depressed is because the surge of the male hormone testosterone in puberty may make them react to the social pressures of teen life in a different way.
"Testosterone can be thought of as a social hormone, and it makes people care about where they stand in the social hierarchy. In boys that may lead them to take risks and do stupid things to gain attention and standing," such as risky driving or drug abuse, "but in girls, caring about what others think may make them depressed and anxious."
Once teens become depressed, the standard treatments are medications or talk therapy, particularly a technique called cognitive behavioral therapy, which tries to get people to change the way they think about their life experiences.
Yet there is one group of depressed younger patients who don't respond well to either of the standard treatments. They have anhedonia (an-he-DOAN-e-ah) -- the inability to experience much pleasure from the activities of daily life.
Dana McMakin, an assistant psychiatry professor at Pitt, is trying a new technique known as "savoring" that might help this treatment-resistant group. It is designed to help them learn how to appreciate and enhance the positive experiences in their lives that in some cases they are almost blind to.
The savoring idea comes out of the fast-growing field of positive psychology, which studies how people achieve happiness and fulfillment. One of the pioneers in that field, Barbara Fredrickson of the University of North Carolina, has found in her studies that people who flourish in life often have three positive emotions for every negative one.
But depressed teens with anhedonia tilt the other direction, the Pitt professor said. Even if they go to an event like a pizza party that they think will be pleasurable, "they often manage to find the one negative event that sours things for them. We don't know exactly why."
People with positive outlooks will often magnify their pleasure by fully experiencing the moment they are in, looking back on a good experience, such as going over photos of a favorite vacation, or anticipating an upcoming one.
The Pitt researcher is helping depressed teens learn how to do that as well, and is doing brain imaging of them in hopes of seeing changes in their brains' reward circuits as a result. One technique she uses is to get them to recall pleasurable experiences by replaying the sights, sounds and other sensations like a "TV in the mind."
"Depressed youths tend to mentally replay negative experiences over and over again," she said, "which can get them stuck focusing on the negative. The hope is that these savoring strategies can shift some focus back toward the positive aspects of life."
For teens with anhedonia, it may be that the normal biases we all have are out of kilter, she said.
Psychology researchers have found that most people have a "positivity offset" and a "negativity bias." What that means, she said, is that "when everything else is sort of calm, we have a general tendency to approach and explore our environment and think things that are coming up may be more wonderful than they are." But our brains are also primed to react quickly when they perceive a threat in the environment.
Many depressed teens seem to lack the upbeat tendency of the positivity offset, she said, and have a hypervigilant negativity bias.
Ms. Silk also is using brain imaging in her work.
In one ongoing experiment, she brings teens with and without depression into her lab and has them play a "social chat" game while lying in a functional magnetic resonance imaging scanner, which charts blood flow to the parts of the brain that are active during different tasks.
Using a set of photos and biographies of peers, the teens choose some to have conversations with about such topics as music or TV shows. While they are in the brain scanner, they sometimes choose whom they want to talk to, but other times they have to see if others will choose them for a particular chat. When they are not chosen for that conversation, an X appears over their own photograph.
The brain imaging has shown that teens who are depressed have a much stronger negative reaction to the times they are not chosen than teens who don't have the disorder. In particular, she said, the regions making up the brain's "threat network" -- including the amygdala, which controls many of our negative emotions, and the subgenual cingulate cortex, which is known to be hyperactive in depression -- kick into gear strongly in the depressed children during those episodes of perceived rejection.
She also has advanced the use of mobile phones and phone apps to check in on teens at random times to get them to record facts about their daily experiences. That work has shown that depressed teens are much more likely to be alone than those who are not depressed, and report almost as many negative emotions as positive ones.
But another interesting and potentially therapeutic fact emerges from the phone monitoring: Depressed teens' day to day lives aren't as different from their peers as they believe.
"I found with the [phone app] research that the differences in how they're spending their everyday lives aren't huge. When you ask the depressed kids in the clinic how their week was, they say 'Oh, it was terrible,' but when you actually assess them in real time it's not as bad as you think it will be."
For teens who are tethered to their mobile phones, this could end up being a way to help them, she said. "From an intervention perspective, I really believe one of the ways we're going to go in the future is using smartphones to intervene in daily life and show them they are feeling happy more often than they think."
Families interested in participating in the teen depression studies can find information at remedyresearchgroup.com.