An official at his high school has said that Sandy Hook shooter Adam Lanza appeared to feel no physical pain, suggesting he may have been congenitally insensitive to it. Research tells us that such conditions can lead to empathy problems. 

Richard Novia served as an advisor to Newtown High School's technology club, an organization to which Lanza belonged. Because club members used soldering tools and other dangerous equipment, Novia says he had meetings with Lanza's mother, Nancy, and school administers about ensuring Lanza's safety, considering his apparent inability to feel pain. "If that boy would've burned himself, he would not have known it or felt it physically," Novia told AP's Adam Geller. 

While we don't yet know if Adam Lanza was ever officially diagnosed with it, these statements square with a condition known as congenital insensitivity to pain, a rare neuropathic disorder that makes people unable to register painful stimuli. And according to UCLA psychologist Elizabeth Laugeson, autism spectrum disorders can sometimes correspond with a reduced sensitivity to pain. Lanza's classmates claim to have been told that he had Asperger's

People with congenital insensitivity mainly experience problems with self-inflicted injuries, but they also sometimes struggle with emotional regulation. The U.S. National Library of Medicine explains:

Unintentional self-injury is common in people with CIPA, typically by biting the tongue, lips, or fingers, which may lead to spontaneous amputation of the affected area. In addition, people with CIPA heal slowly from skin and bone injuries ... About half of people with CIPA show signs of hyperactivity or emotional instability, and many affected individuals have intellectual disability.

Certain studies suggest that people who can't feel pain may empathize with others differently than people with normal pain thresholds. A team of French researchers led by Nicolas Danziger of Pitie-Salpetriere Hospital recently studied this phenomenon using brain-imaging technology, seeking to answer a simple question: Can someone empathize with another's pain when they've never felt it themselves?

To find out, they separated subjects into two groups—one comprised of people who feel normal amounts of pain, and another made of people with congenital insensitivity to pain. They hooked up subjects to functional magnetic resonance imaging (fMRI) machines and asked them to look at pictures of people caught in painful situations. They found that while CIP subjects had lower brain activity in the visual regions, midline brain structures lit up visibly in members of both groups. They concluded that CIP patients have a hard time with mirror matching—empathizing with others based on past experiences. But many could still empathize through perspective taking, a "means for understanding others’emotions in a more reflective way."

Not all people who suffer from an inability to feel pain have empathy problems, though. Just last month The New York Times Magazine ran a cover story on a Georgia teenager who can't feel pain. Thirteen-year-old Ashlyn Blocker had been given "a range of psychological tests to determine if she could feel emotional pain and empathy" by her doctor. "He found her to be a bright and friendly child," Justin Heckert reports.