First there’s the one-word answers, then the sullen silence, then lashing back – finally the slamming of the door to their bedroom. When your teenage kid starts to get moody, irritable, or lashes back at you – do you write it off as just a phase, or do you begin to worry if there is something seriously wrong with them?

Many parents who deal with difficult adolescents often find themselves wondering what happened to the lighthearted, open, happy child they used to know. Psychologists are split on the issue: some believe it’s more often than not just a phase every child goes through, while others believe these behavior changes should be taken more seriously as a sign of an underlying mental illness. A study published in the journal Developmental Psychology, however, may shine some light on the issue: Dutch researchers found that teen boys between the ages of 13 and 16 actually had decreased levels of empathy, or the ability to understand and feel other people’s emotions, and that it may have something to do with a teenager's moodiness.

Empathy And Perspective

Researchers examined 500 teenage boys and girls between the ages of 13 and 18 over the course of 6 years. They found that among girls, cognitive empathy – the ability to understand and consider another person’s perspective – rose around age 13, and remained relatively stable throughout these years. Overall, girls had a higher level of empathic concern than boys, whose empathy levels dropped for several years before returning again in later teenage years. “Whereas girls’ empathic concern remained stable… boys showed a decrease from early to middle adolescence with a rebound to the initial level thereafter,” the authors wrote. “Boys who were physically more mature also reported lower empathic concern than did their less physically developed peers.”

Other studies have examined the issue of empathy in young people. One study hinted that the current generation is far less empathetic as a whole – no matter what age. The study reviewed 14,000 college students, claiming that young people today are 40 percent less empathetic than college students 30 years ago. One of the lead authors of the study even said that “[i]t’s harder for today’s college student to empathize with others because so much of their social lives is done through a computer and not through real life interaction.”

Mental Health Of Adolescents

Whether lack of empathy is truly an epidemic in today’s generation, or if it’s just a short phase every adolescent goes through before reaching full adulthood, it can make parents worry about their child’s mental well-being. Moodiness can often be mistaken for severe depression or mental illness, and vice versa. And there are some psychological experts who believe that the idea of a “phase” teenagers go through is just a myth – that there actually is an underlying mental illness accompanying these symptoms or seemingly changed personality.

“The tendency of parents is to think ‘This is normal,’ ‘They’ll outgrow this,’ ‘Not to worry,’” Alec Miller, a doctor of psychology and chief of child and adolescent psychology at Montefiore Medical Center in NYC, told NBC News. “As a parent you can really lose your compass about what’s normal and typical when you have a range of behaviors coming at you.”

What most experts agree upon, however, is that a clear sign of mental illness is typically when moodiness or irritability begins interfering with an adolescent’s life, such as causing them to skip class, withdraw from friends, or start eating or sleeping differently. “Parents will often let this go at least two weeks or more because they’re convinced it’s just a phase, even though if their child has a rash, they wouldn’t ignore it,” Dr. Harold Koplewicz, founder and director of New York University Child Study Center, told NBC News.