Capturing the earliest stages of Dementia especially Alzheimer's Disease (AD) is a great challenge. Until now the NINCDS-ADRDA and the DSM criteria for AD were largely used as diagnostic standards in research. However, the research on AD progresses and some biomarkers have been recently suggested to improve the diagnostic criteria of AD, such as cerebrospinal fluid markers, neuroimaging with Positon Emission Tomography (PET) or Magnetic Resonance Imaging (MRI).