The Phase II randomized controlled trial by Rafii et al. (2018) using AAV2-NGF (CERE-110) failed to produce statistically significant improvements in cognitive endpoints such as Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) or Mini-Mental State Examination (MMSE) over a 24-month period. This evidence concerns the gene NGF and Alzheimer disease.