MAPT and Alzheimer disease: This research framework groups fluid and imaging biomarkers into the so-called AT(N) classification: “A”, for biomarkers of aggregated Aβ, including cerebrospinal fluid (CSF) Aβ42, CSF Aβ42/40 ratio and Aβ-PET; “T”, for biomarkers of aggregated tau (NFTs), comprising CSF phosphorylated tau at threonine 181 (p-tau181) and tau-PET; and “(N)” (N biomarkers are not AD specific and therefore appeared in parenthesis), for biomarkers of neurodegeneration or neuronal injury, specifically CSF total-tau (t-tau), MRI and FDG PET [5].