An ANKS1A-A355D protein variant is found in Alzheimer's disease patients, and unlike a normal ANKS1A protein, is unable to induce the cell membrane expression of an LRP1 receptor, and thus is unable to efficiently remove toxic proteins such as an amyloid beta peptide. Therefore, provided is a method for providing early diagnosis information on the onset of Alzheimer's disease by confirming the expression level of an ANKS1A-A355D protein variant or detecting the presence or absence of a gene encoding the ANKS1A-A355D protein variant. Also, provided is a composition comprising an agent for detecting an ANKS1A-A355D protein variant or a polynucleotide encoding same.
