EEG coherence in alzheimer and multi-infarct dementia

Summary us studies using quantitative EEG (qEEG) absolute and relative power did not reveal significant differences between Alzheimerʹs dementia (AD) and multi-infarct dementia (MID); several studies have reported differences in qEEG coherence which could be of some diagnostic utility. Aim of this study is to compare EEG coherence in AD and MID in order to evaluate, if topographic changes of coherence could differentiate the two major types of dementia. We examined 61 AD and 41 MID patients. Alpha coherence was significantly decreased in both groups while delta coherence was increased especially in MID patients. However, topographic distribution of coherence alterations were different in the two groups. In fact, the reduction of alpha coherence was diffuse or multifocal in MID and more evident in centro-anterior regions in AD: the increase of delta coherence was diffuse in MID and in the left posterior regions in AD. The decrease of alpha coherence in AD, could be considered an involvement of long cortico-cortical connections and the decrease of alpha coherence in MID, as an involvement of short cortico-cortical connections.