It's no surprise to most that Germanwings Flight 9525 co-pilot Andreas Lubitz, who crashed the plane into a mountain, killing all of the passengers and crew, had been treated for suicidal tendencies. 

While publications such as Slate rush to declare that depression is not linked to suicide, the actual mental health community notes that those issues are linked and usually start during adolescence, so we need a better way to measure depression severity to ensure proper treatment. At present the key symptom for diagnosing major depressive disorder in adolescents is irritability, but a new study has found that the severity of anhedonia (the inability to gain pleasure from experiences that usually are enjoyable) rather than of irritability is associated with more severe  major depressive disorder  and worse clinical outcomes and suicide scores. 

Vilma Gabbay, MD, and coauthors at Icahn School of Medicine at Mount Sinai and New York University Langone Medical Center (New York, NY), and Nathan S.. Kline Institute for Psychiatric Research (Orangeburg, NY), used a quantitative approach to focus on symptoms of irritability and anhedonia simultaneously in 90 adolescents with MDD. Only anhedonia severity showed a significant correlation with the severity of overall outcomes, including illness severity, episode duration, and number of MDD episodes.

The authors emphasize the importance of closely monitoring highly anhedonic depressed adolescents.

Citation: Gabbay Vilma, Johnson Amy R., Alonso Carmen M., Evans Lori K., Babb James S., and Klein Rachel G., Anhedonia, but not Irritability, Is Associated with Illness Severity Outcomes in Adolescent Major Depression, Journal of Child and Adolescent Psychopharmacology doi:10.1089/cap.2014.0105