Use of an ErbB2 inhibitor for promoting ErbB2-regulated autophagic degradation or clearance of APP-C99 and APP intracellular domain (AICD) and/or alleviating production of Abeta 40 and Abeta 42 in a subject in need thereof is disclosed. Use of an ErbB2 inhibitor for rescuing ErbB2-mediated inhibition of autophagic flux in a subject in need thereof is also disclosed. Use of an ErbB2 inhibitor for enhancing spatial learning and memory, and/or for cognitive improvement, in a subject with ErbB2-associated Alzheimer's disease is further disclosed. Also disclosed is use of an ErbB2 inhibitor for reducing intracellular levels of C99 and AICD without affecting extracellular domain-truncated Notch and Notch intracellular domain in a subject in need thereof.