Topography of mobility and complexity parameters of the EEG in Alzheimer's disease.

Mobility and complexity, Hjorth's parameters of the electroencephalogram (EEG), were calculated in 16 electrodes in a group of 14 patients with probable Alzheimer's disease (AD) and 14 healthy controls. Mobility was decreased in the AD group, differences reaching high levels of significance over all the electrodes. Complexity was increased significantly in the AD group only in five electrodes. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for mobility at each electrode, considering only those AD patients with the lowest cognitive impairment. Sensitivity and negative predictive value were 100% at all the electrodes. Specificity and positive predictive value at several electrodes reached highly acceptable proportions, such as 71% or more for the former, and 64% or more for the latter. Implications of mobility in the early diagnosis of AD are discussed.