What Made Maddy Run?” That’s the title question of a new book about a suburban New Jersey teen and track star, Madison Holleran, who committed suicide in 2014 during her freshman year at the University of Pennsylvania. The real question, though, is: What made Maddy stop?

Depression is a difficult problem to diagnose and treat, and there are probably many factors that led to this tragedy. But it is striking that, despite Maddy’s strong social network, as well as her success both academically and athletically, she felt a crushing pressure, one that’s becoming more and more common — for teenage girls, especially.

With the help of Maddy’s family, friends and teammates, who were shocked and baffled by this tragedy, espnW columnist Kate Fagan tries to recreate the last several months of her life not only through interviews with those who knew her but also by looking through all of her text messages, e-mails and social-media posts.

One might think these messages would offer a glimpse into Maddy’s innermost thoughts, but Fagan concludes the opposite.

“Maddy was in constant contact with dozens of friends and family, a skimming of the surface covering miles and ground but very little depth. And through all those messages to all those people, thousands and thousands of communications, almost nobody noticed anything significantly amiss.” Indeed, it may be that the constant need to show everyone that she was alright, that her life was almost perfect, contributed to the problem.

Fagan, who struggled with anxiety and depression during her own years playing college basketball, describes how the amount of time we spend online and finding ways to present ourselves on social media creates more problems than it solves.

“In the past few years,” Fagan writes, “I’ve spent almost as much time constructing and maintaining my online self as I have my real, human self . . . Sometimes it feels much easier to live in that reality than in the one where I am always flawed and challenged, and occasionally sad . . . It is easier to feel connected online than to truly connect in real life. So plugging in becomes addicting.”

This is a problem that extends far beyond student athletes. In her new book, IGen, an excerpt of which appears in The Atlantic next month, psychologist Jean Twenge notes that kids born between 1995 and 2012, are “more vulnerable than Millennials were: Rates of teen depression and suicide have skyrocketed since 2011.”

After looking at data from large-scale surveys about teen attitudes and behaviors — including one that has asked the same 1,000 questions every year since 1975, Twenge writes, “It’s not an exaggeration to describe iGen as being on the brink of the worst mental-health crisis in decades. Much of this deterioration can be traced to their phones.”

After examining the effects of screen time on mental health, Twenge says this isn’t surprising.

“All screen activities are linked to less happiness, and all nonscreen activities are linked to more happiness.” She notes, “If you were going to give advice for a happy adolescence based on this survey, it would be straightforward: Put down the phone, turn off the laptop and do something — anything — that does not involve a screen.”

We often think that such advice applies only to kids who seem to be uninvolved in school or sports, kids who have few friends and just seem to be spending too much time on video games or in chat rooms. But the truth is that no matter where you are in the social stratosphere, social media has a significant effect on your life.

If you’re attractive and popular, there’s a great deal of pressure to make sure that your life looks perfect online. If you’re not, there’s a sense you are always being left out. The percentage of teens who say that they “often feel lonely” or “left out” reached a 25-year high in 2015.

Though teens today may be more closely monitored by parents than those of previous generations, and may be safer in many respects — they’re less likely to drive drunk or have multiple sexual partners — they’re also disconnected from those around them.

One of the girls Twenge interviews, “Athena,” is representative. “Like her peers, Athena is an expert at tuning out her parents so she can focus on her phone. She spent much of her summer keeping up with friends, but nearly all of it was over text or Snapchat. ‘I’ve been on my phone more than I’ve been with actual people,’ she said. ‘My bed has, like, an imprint of my body.’?”

But she’s upset that her friends aren’t really listening to her because they’re on their phones all the time. She tells Twenge, “It hurts . . . I could be talking about something super important to me, and they wouldn’t even be listening.” After reading Maddy’s story, that’s a fear that should haunt all of us.