Preface: Mass spectrometry in Alzheimer disease: This is the Preface for the special issue "Mass Spectrometry in Alzheimer Disease".

This preface introduces the content of the special issue on 'Mass Spectrometry in Alzheimer Disease'. Here, an overview is provided on how mass spectrometry is contributing to a broader understanding of AD pathobiology. Mass spectrometry has become a major technology in biomedical analysis and research. This includes biochemical and clinical studies that aim to detail our understanding of Alzheimer disease pathogenesis and pathobiology (AD). In this special issue, key experts in the field present exciting developments and applications of MS in the context of studying AD pathology. These studies span from basic biochemical and neuropathological studies, over advanced metabolomics- and proteomics, towards comprehensive biomarker studies, as well as more recently, in situ mass spectrometry-based imaging (MSI). Together, these studies highlight the key relevance of current and emerging MS technologies to detect, delineate and understand principle pathogenic mechanisms underlying AD.