Stages of Disease
There are two questions most often asked:
"What is next?" and "How do I plan for the future?"
These are very hard questions to answer, since the duration of illness in HD patients beyond the time of motor symptom diagnosis can be as short as 10 years or as long as 25 years. A practical way of determining the course of disease is to measure functional ability. Total Functional Capacity, TFC, is a measurement done as part of many Huntington Study Group research studies. It is unfortunately not a very good measure early in the course of disease when most abilities are preserved. Although symptoms during the early stages may be bothersome, they don’t interfere with the overall ability to work or with personal care. Late in the course of disease, Total Functional Capacity is also not a good way to measure progression, since the duration of life after a person requires total care for activities of daily living (ADLs) varies based on quality of medical and nursing care and other health variables. It is, however, very useful to evaluate functional abilities during the middle stages of the disease, since this is the period of time in which patients need help with some things, and are independent in other areas.
TFC has been measured in a large group of people with HD over time, and shows that the average patient declines approximately 0.7 units per year. Another way of looking at this is that the rate of decline over the previous year or two predicts the rate of decline in the coming years. It is also useful to measure TFC because a sudden change in the rate of decline can signal the need for investigation of factors not related to HD, such as infection, overmedication, risky health behaviors, or a problem with environment, such as overstimulation or stress in the home.
