BACE1 and Alzheimer disease: For example, in AD treatment studies, multifunctional nanocarriers (Rapa@DAK/siRNA) delivered BACE1 siRNA to the brain via the nasal route, significantly reducing BACE1 expression and decreasing β-amyloid (Aβ) deposition by activating the autophagy pathway, ultimately improving cognitive function in transgenic AD mice [39].