IGHE and Alzheimer disease: Evidence directly comparing PN and AD in Chinese populations remains limited.<h4>Objectives</h4>To characterize clinical distinctions between PN and AD in Chinese adults and to explore whether total serum immunoglobulin E (IgE) status delineates distinct clinical profiles within PN.<h4>Methods</h4>This multicenter case-control study enrolled 2,621 adult patients (≥18 years) including 1,462 with PN and 1,159 with AD.