Mr. Watts went to see Dr. Pass, a specialist in sleep disorders, because of his history of violent behavior during sleep. Although Mr. Watts didn't have any complaints, his wife was extremely frightened by the episodes of shouting, kicking, and punching that would occur while her husband was sleeping, usually in the early morning hours. After conducting a thorough history and physical exam, Dr. Pass was certain that the diagnosis was idiopathic REM sleep behavior disorder. Although Mr. Watts had always been healthy, Dr. Pass had seen in the literature that, with this diagnosis, Mr. Watts—now 58 years old—had a significant chance of developing a neurodegenerative disease within the next 10-15 years. He wondered whether he should tell Mr. Watts about his risk, given that there was some chance that he would not develop neurodegenerative disease. Whether or not he developed more serious disease later, Mr. Watts, currently an active, working attorney, might experience depression and grief if he were informed of this possibility. To complicate matters even more, there was nothing Mr. Watts or Dr. Pass could do now to prevent or delay onset of the disease.