P‐130: Clinical criterion of MCI

Abstract

The scalp potential distribution of the spontaneous EEG alpha component (3 Hz bandwidth) in the rest state with eyes closed is well approximated by a potential distribution generated by a single current dipole, and the goodness-of-fit, Dα, takes a value close to unity in normal subjects. The cortical synaptic-neuronal activity of an AD patient is partially and slightly impaired, as a result of which the scalp potential distribution is distorted, hence Dα is lowered. This potential distortion is very sensitive to the impairment. In our previous study the Dα range is divided in three regions: normal (0.96 < Dα < 1), subnormal (0.94 < Dα < 0.96) and impaired (0.85 < Dα < 0.94); the range below is not our interest because it no longer belongs to the early stage. This method of detecting neuronal impairment is called DIMENSION (Diagnosis Method of Neuronal Dysfunction). MCI is a state that is neither normal nor demented but the brain activity is gradually lowered. We propose a method of discriminating MCI in terms of a change in the Dα value and the MMSE score observed across a period of six months. Scalp potentials on 21 sites are collected for 5 min in a rest state with closed eyes and the Dα value is calculated via the Internet. The result is graphically displayed on a computer display. This method is so sensitive that a temporal brain activation after a single rehabilitation is easily detected. If the MMSE score remains between 25 and 30 but the Dα value is lowered significantly or more than 0.005 during a 4∼6 month period, it is probable that the patient is in MCI. DIMENSION is a method of detecting a change of cortical synaptic-neuronal impairment in the early stage of brain disorders that is inexpensive, non-invasive, sensitive, reliable, and easy to operate. If Dα value decreases more than 0.005 during 6 months while the MMSE score remains in 25∼30, it is probable that a person under test is in MCI. Thus the MCI screening can be done easily and economically.