"Symptoms of Huntington's disease can vary between individuals and among affected members of the same family, but the symptoms progress predictably for most individuals. The earliest symptoms are a general lack of coordination and unsteady movements. As the disease advances uncoordinated, jerky body movements become more apparent, along with a decline in mental abilities and behavioural and psychiatric problems. Physical abilities are gradually impeded until coordinated movement becomes very difficult. Mental abilities generally decline into dementia. Complications such as pneumonia, heart disease, and physical injury from falls reduce life expectancy to around twenty years after symptoms begin. Full-time care is required in the later stages of the disease."
Hungtington's Disease Association UK