NGF and Alzheimer disease: However, it has been reported that in pathological conditions, such as those found in Alzheimer's Disease, the NGF metabolic pathway is impaired, with a reduction in proNGF processing and a concomitant increased NGF degradation (Pentz et al., 2021) and increased proNGF levels found in AD correlate with the severity of the disease (Counts & Mufson, 2005).