At present, this is mainly to assess for Alzheimer biomarkers in CSF (elevated phospho-tau, total tau and tau:beta-amyloid1–42 ratio; reduced beta-amyloid42:40 ratio) or on radio-ligand positron emission tomography with Pittsburgh compound B or fluorine 18-labelled tracers (florbetapir, florbetaben, and flutemetamol) (increased uptake with binding of beta-amyloid plaques), as this may help guide a trial of symptomatic therapy for Alzheimer’s disease. This evidence concerns the gene MAPT and Alzheimer disease.