Experimental medicines related to ketamine, an anesthetic and club drug, are making progress in clinical tests. Wikipedia hide caption

itoggle caption Wikipedia

About twice a year, statistics suggest, a pilot somewhere in the world — usually flying alone — deliberately crashes a plane. The Germanwing flight downed last week may be one such case. But most people who fit the psychological profile of the pilots in these very rare events never have problems while flying. Patrik Stollarz/AFP/Getty Images hide caption

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A University of Missouri study shows that if your Facebook lurking triggers envy, then depression may follow. Adam Hester/Blend Images/Corbis hide caption

itoggle caption Adam Hester/Blend Images/Corbis

Sgt. Mark Miranda, a public affairs specialist at Joint Base Lewis-McChord in Washington state, demonstrates the use of a program in July 2011 that was designed to help calm symptoms of post-traumatic stress and traumatic brain injury. A new class of apps is offering more sophisticated mental health help to struggling teens, including emergency, 24/7 connection to counselors. Ted S. Warren/AP hide caption

itoggle caption Ted S. Warren/AP

One of the scariest parts of advanced macular degeneration can be losing the ability to read facial expressions. Maria Pavlova /iStockphoto hide caption

itoggle caption Maria Pavlova /iStockphoto

Teenagers' sleep patterns may be a clue to their risk of depression. iStockphoto hide caption

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Girls are particularly vulnerable to brain changes caused by stress or trauma, researchers say. Allen Johnson/ hide caption

itoggle caption Allen Johnson/