抄録
EEG examination was performed on 205 healthy old persons of more than 50 years of age who were engaed in their busineses, and the following results were obtained. 1) Abnormal EEG appeared more frequently as the subjects grew older. Its incidence was higher in women than in men. 2) The frequency of the basic wave in the posterior half of the brain decreased with advancing age. 3) The lowest and highest frequency of the basic waves were examined according to the age groups; cycles below 8.0 cps appeared most frequently in the seventies, less frequently in the sixities and least frequently in the fifties. 4) The appearance of the fast wave was most conspicuous in the sixties. 5) The incidence of the diffuse slow wave was less than 1 per cent. 6) The focal abnormal wave appeared in most cases in the temporal region.
