Neurofunctional assessment of early phases of Alzheimer's disease: a preliminary note on hemispheric EEG characteristics during cognitive tasks.

EEG characteristics, in terms of power distribution in 1-4, 4-6, 6-8, 8-10, 10-13, 13-18, 18-30 Hz frequency bands were evaluated in six putative non-medicated male Alzheimer patients. The latter were compared with six age and sex-matched normal controls during both resting conditions and tactile identification tasks specific for the left and right hemispheres. The result indicate a significant difference in the power of the 8-10 frequency band between the two groups and a significant hypovariability in the 6-8 and 8-10 bands during tactile tasks: Alzheimer patients showed reduced power and, also, where less reactive, no differences between the left and right hemispheres having appeared. These findings seem to confirm the specificity of EEG modifications in Alzheimer's disease, even in the very early phases of the pathological process. Possible implications are discussed in the light of some biochemical hypotheses.