HD is an inherited, progressive disease. It causes nerve degeneration, motor disturbance, loss of awareness, and psychiatric symptoms. Currently, no effective treatment is available to prevent or delay HD progression. The mean age of onset is 35 to 44 years, and the median survival rate after onset is 15 to 18 years. HD affects about 1 in 10,000 people in the United States, so about 30,000 have HD and more than 200,000 are at risk. Predictive testing for HD has been available since 1993. It can be a life-changing event to learn of being at risk for HD. Disclosure has been studied among people with HD and other diseases, but knowledge about the extent of nondisclosure and disclosure is limited. There is evidence that a person s psychological adaptation to AD may be a factor. Adaptation involves processes that help a person search for meaning in what has happened, attempt to gain control of his or her life, and improve self-esteem in light of the threatening situation.