A double-blind sham surgery-controlled trial was conducted to determine the effectiveness of implantation of human embryonic dopamine neurons into the putamen of patients with advanced Parkinson's disease (PD), with half the patients receiving the implant (n = 20) and half receiving sham surgery (n = 20). The goals were to determine whether the cells survived and led to improvement of symptoms, and to examine the effect of age on results of the implantation. Quality of life of participants and care partners was also examined at each of the assessment periods (baseline, 4, 8 and 12 months). The blind was maintained for 12 months.
