Alzheimer’s is considered a disease of old age, with most people being diagnosed after 65. But the condition actually begins developing out of sight many years before any symptoms emerge. Tiny proteins, known as amyloid-beta peptides, clump together in the brain to form plaques. These plaques lead to inflammation and eventually cause neuronal cell death. Exactly what triggers these pathological changes is still unclear. “We’re lacking good diagnostic markers that would allow us to reliably detect the disease at an early stage or make predictions about its course,” says Professor Erich Wanker, PhD, head of the Proteomics and Molecular Mechanisms of Neurodegenerative Diseases Lab at the Max Delbrück Center. Dr. Wanker and his team are studying brains with Alzheimer’s disease to understand their proteome--he interplay between all the proteins involved in the onset and course of the disease. Writing in Genome Medicine on July 19, 2023, the researchers now report on a new actor in the pathological process. Their discovery will help scientists understand the mechanisms underlying Alzheimer’s and could also serve as a marker for improved diagnostics. The open-access article is titled “A Proteomics Analysis of 5xFAD Mouse Brain Regions Reveals the Lysosome-Associated Protein Arl8b As a Candidate Biomarker for Alzheimer’s Disease.” To analyze changes in the proteome, Dr. Wanker’s team studies genetically modified mice. The mice have five mutations that occur in people with familial Alzheimer’s disease. The amyloid-beta plaques develop in the mice’s brains and the animals show typical symptoms, such as dementia.