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Being plugged into an iPod is a hallmark of adolescence, but a new study suggests that teens who spend too much time listening to music may be at higher risk of depression.

The study, led by Dr. Brian Primack, an assistant professor of medicine and pediatrics at the University of Pittsburgh School of Medicine, found that teens who reported listening to music more often — rather than using other types of media like TV and books — were at higher risk of having major depressive disorder (MDD), compared with teens who listened to music less frequently. With each level increase in music use, teens had an 80% higher risk of depression, the study found.

The study didn’t measure total listening times, but based on previous data, the study authors estimated that teens in the highest-use group were likely listening to music for at least four or five hours a day. (More on TIME.com: Psychological Problems in Childhood Affect Earning Power and Relationships Later)

“At this point, it is not clear whether depressed people begin to listen to more music to escape, or whether listening to large amounts of music can lead to depression, or both,” said Primack in a statement.

By contrast, researchers found that reading books had the opposite association: with each level increase in time spent reading, teens’ risk of depression dropped 50%. “This is worth emphasizing because overall in the U.S., reading books is decreasing, while nearly all other forms of media use are increasing,” Primack said.

For the study, the researchers surveyed 106 participants aged seven to 17 for two months; 46 participants had been previously diagnosed with depression. Throughout the course of the study, researchers made frequent weekend phone calls to the teens in order to determine, in real time, what forms of media they were using, including television, music, video games, Internet, magazines and books. (More on Time.com: Kids Under 6 Get Online Every Day)

On average, teens were most likely to be watching a movie or TV when researchers called (26% of the time). Teens reported listening to music 9% of the time, followed by Internet use and video gaming (6% each) and, finally, reading printed media (0.2%). (Sadly, the researchers wrote: “Because there were so few individuals who used magazines and/or newspapers, we combined these data with books into a single print media category.”)

Of all the media reported, only music showed significant associations with increased depression risk, after researchers controlled for factors like age, sex and ethnicity. But that doesn’t necessarily mean that music causes depression — for some depressed teens, music may even help. The authors explain:

[S]adness is a common theme in popular music, and it may be that individuals with depression turn to these messages to make themselves feel less alone in their sadness. Conversely, it may also be that individuals with MDD turn to happy music to “tune out” their negative moods or to elevate their moods. Other researchers have suggested that heavy exposure to the sometimes dark themes of popular music may contribute to the development of conditions such as MDD.

Past research has also found links between depression and other forms of media like TV and video games. A seven-year study published in 2009, also led by Primack, showed that teens who watched more TV were more likely to become depressed in adulthood, compared with teens who watched less. So the researchers were surprised to find no such association in the current study, but suggest that further research is necessary to clarify potential links. (More on TIME.com: Pediatricians Should Discuss ‘Facebook Depression’ with Kids)

Previous longitudinal research has also found that reading may have a mentally protective effect: teens who read more are less likely to become depressed as adults. The current study suggests that being depressed may also preclude time spent reading. “We sort of thought to ourselves that when you have depression, your brain is not working properly. So it’s much harder to sit down to a book and have to use a lot of the frontal lobe of your brain to create the story and the characters in your head, whereas, it should be quite easy to flop down in front of a television and turn on whatever’s there,” Primack told WebMD.

Although the connections between depression and various forms of media are significant, more research is needed to understand them better, especially considering the conflicting information. (More on TIME.com: Misery Loves Company, Especially on Facebook)

But for now, Primack said the findings may be a way for parents to spot a potentially troubled teen. “It may be valuable for people to help pick up cues for common behaviors like listening to music,” he said.

The study is published in the April edition of the Archives of Pediatric and Adolescent Medicine.

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