[Electroencephalography, a potential biomarker for early diagnosis of dementia].

: Early diagnosis at the prodromal stage of dementing illnesses is an important topic of current clinical research. Remarkable advances of biomarker for the early diagnosis have done with structural MRI imaging, metabolic/amyloid PET imaging, and cerebrospinal fluid analysis. However, there still remains a need to develop an efficient, low cost, portable, noninvasive method. Electrophysiological measurements are promising for this point and they have the highest time resolution for reflecting brain dynamics in cognition. Unfortunately, the classification of cognitive impaired subjects at individual level revealed a moderate accuracy with electrophysiological markers. However, cortical functional activity change preceding anatomical and metabolic changes can only be assessed by electrophysiological measurements. Improvement of the accuracy for the early diagnosis of cognitive decline is expected.