Unusual grimaces are normally the first sign that something is wrong. Next, affected people become more and more absentminded and begin to display involuntary gestures, especially when under psychological or physical stress. As the disease progresses, the dancelike movements--which may be confused with drunkenness--
occur more frequently and become disabling. People lose their capacity to perform simple, everyday tasks and show impairments in intellectual abilities such as planning. In the later stages, depression and aggressiveness--and, in the most severe cases, dementia and psychosis--take over, reducing a formerly healthy, vital family member, friend or co-worker to a miserable, bedridden shadow.