Joni Mitchell, 71, was taken to a hospital in Los Angeles on Tuesday after she was found unconscious at her Los Angeles home. In recent years, the singer has complained of a number of health problems, including one particularly unusual ailment: Morgellons disease. People who believe they have the condition report lesions that don't heal, fibers" extruding from their skin and uncomfortable sensations like pins-and-needles tingling or stinging. Sufferers may also report fatigue and problems with short-term memory and concentration. But Morgellons is not a medically accepted diagnosis. Researchers at the Centers for Disease Control and Prevention studied 115 people who said they had the condition. In a report published in 2012, they said they were unable to identify an infectious source for the patients' "unexplained dermopathy." The investigators cast doubt on Morgellons as a distinct condition and said that it might be something doctors were already familiar with: delusional infestation, a psychiatric condition characterized by an unshakable but erroneous belief that one's skin is infested with bugs or parasites. These patients have a reduced quality of life, the researchers concluded, but the cause is not clear. Science one day may find that Morgellons has a physical basis, but at the moment most experts treat it as a psychiatric disorder - to the great frustration of people, like Ms. Mitchell, who ... are afflicted with it.