On the Clinical Trials website, the "young plasma for PD" trial has an estimated Study Completion Date of December 2018. Unfortunately, I think we can expect to wait another year or two for the research paper(s) to emerge.
The Stanford Parkinson's Disease Plasma Study - Full Text View - ClinicalTrials.gov

Meanwhile, the "young plasma for AD" trial (Study Completion Date: February 2017) has recently published a research paper [1]. The research paper is behind a paywall, but here is an article about it.
Young Fresh Frozen Plasma Proves Feasible for Alzheimer Symptom Amelioration

[1] Sha SJ, Deutsch GK, Tian L, et al. Safety, tolerability, and feasibility of young plasma infusion in the plasma for Alzheimer symptom amelioration study: a randomized clinical trial. JAMA Neurol. epub October 29, 2018. doi: 10.1001/jamaneurol.2018.3288.
Safety, Tolerability, and Feasibility of Young Plasma Infusion in the Plasma for Alzheimer Symptom Amelioration Study: A Randomized Clinical Trial. - PubMed - NCBI