The three major brain hallmarks of Alzheimer’s disease (AD) are extracellular amyloid plaques, axonal degeneration and intraneuronal neurofibrillary tangles, which can all be monitored via changes in the cerebrospinal fluid (CSF) biomarkers amyloid beta 42 (Aβ42), total-tau (T-tau), and phosphorylated-tau (P-tau). Within this article we have an insight into the world of in Alzheimer’s Disease`s by Henry J. Riordan, from Worldwide Clinical Trials, and Neal R. Cutler of Worldwide Clinical Trials.