MAPT and Alzheimer disease: Patients with AD have low β-amyloid level protein and high total tau and phosphorilated tau in the cerebrospinal fluid (CSF).49 The CSF levels of the isoform with 42 aminoacids of β-amyloid protein and tau protein (total tau and phosphorilated tau) are strongly related with AD neuropathology and are considered the gold-standard biomarkers in differentiating AD from dementia of other causes and psychiatric disorders,49,50 as depicted in Table 1.