NRGN and Mental deterioration: We and others have previously shown that the ratio between Ng and BACE1 (Ng/BACE1) is increased in subjective cognitive decline (SCD) and mild cognitive impairment (MCI) with amyloid plaques, and is more strongly related to hippocampal volume, cognitive impairment and decline as compared to Ng alone.17,38 However, Ng and BACE1 levels in patients with only amyloid plaque pathology (A+/T−/N−) has not been compared to more advanced stages (i.e. A+/T+/N+).