A lot of things that basically boil down to budget, optimization and space available. If you have a drug that you believe you can show a strong effect with the

A lot of things that basically boil down to budget, optimization and space available. If you have a drug that you believe you can show a strong effect with the effect group at ~15 people, maybe you run the trial with 40 (15 e.g., 15 control, plus wiggle room for drop-outs over the 18-month course and extra certainty). Check the last few paragraphs--"The authors thank Shayna Greenberg, Dev Darshan Khalsa, and Anya Rosensteel for help in recruitment, data management, and study coordination; John Williams, University of California, Los Angeles, Nuclear Medicine Clinic, for performing the PET scans; and Vladimir Kepe, Cleveland Clinic, for developing the FDDNP-PET analysis procedures for proteinopathies in patients with neurodegenerative diseases." Add all that to the effort involved in the actual chemical extraction of the bioavailable curcumin analogue and it just doesn't make sense to add any more people than you need.