Clinical trials are part of the research pipeline to treatment
for Huntington's disease. Before a compound can be prescribed
for HD patients, it must go through three phases of clinical
trials. In Phase I, a small number of volunteers are given the
drug and closely monitored to see whether the drug is safe and
well-tolerated. Phase II involves more volunteers and focuses on
finding the correct dose. Safety and tolerability continue to be
monitored. Phase III involves a still larger group - several
hundred in HD research. Volunteers are randomly assigned to
either the treatment group or a control group who receives a
placebo (a non-active compound, sometimes a sugar pill). The
study is double blinded - neither the subjects nor the
researchers assessing them will know who received the compound
and who received a placebo until the end of the study. Phase III
takes much longer since enough time must pass for differences in
disease progression to emerge between the treatment group and
the control group, assuming t