To quantify the severity of clinical symptoms and cognitive dysfunction, clinical assessment scales and cognitive tests are used in clinical studies involving patients with Alzheimer's disease (AD). As an increasing number of clinical studies involving individuals with preclinical AD and mild cognitive impairment are being conducted, newly developed scales are also utilized in those studies. Scales and tests must be translated into Japanese and validated, with the level of difficulty kept equal to the original, in order to obtain data comparable to those of other countries, in global studies. Moreover, the uniformity of procedures in test administration is crucial to procuring high-quality data in multicenter clinical studies. Such background efforts, which support novel scientific findings, as well as clinical assessment scales and cognitive tests which are used in recent studies are described in this section.