EEG COHERENCE IN ALZHEIMER AND MULTIINFARCT DEMENTIA

Previous studies using quantitative EEC (qEEG) absolute and relative p ower did not reveal significant differences between Alzheimer's dement ia (AD) and multi-infarct dementia (MID); several studies have reporte d differences in qEEG coherence which could be of some diagnostic util ity. Aim of this study is to compare EEG coherence in AD and MID in or der to evaluate, if topographic changes of coherence could differentia te the two major types of dementia. We examined 61 AD and 41 MID patie nts. Alpha coherence was significantly decreased in both groups while delta coherence was increased especially in MID patients. However. top ographic distribution of coherence alterations were different in the t wo groups. In fact, the reduction of alpha coherence was diffuse or mu ltifocal in MID and more evident in centro-anterior regions in AD: the increase of delta coherence was diffuse in MID and in the left poster ior regions in AD. The decrease of alpha coherence in AD, could be con sidered an involvement of long cortico-cortical connections and the de crease of alpha coherence in MID, as an involvement of short cortico-c ortical connections.