In addition to disease-specific biomarkers, like CSF, plasma, and PET biomarkers, as well as tissue biopsies to assess specific pathological proteins (tau, Aβ, αSyn, etc.), disease-non-specific biomarkers (neuroimaging, MRI, SPECT, electrophysiology, blood biomarkers like NfL, GFAP, etc.)are intended to reflect pathological changes caused by co-pathologies, like brain atrophy, neuronal and synapse dysfunction and loss, metabolic disorders, or biochemical abnormalities. Here, NEFL is linked to metabolic disease.