ANALISI DELLA COERENZA NELLA MALATTIA DI ALZHEIMER

The analysis of EEG coherence allows to study coupling of bioelectrical activity of different cerebral areas and gives informations about inter and intra-hemispheric connections. EEG coherence, at rest, has been evaluated with an AutoRegressive parametric model in 10 patients affected by probable Alzheimer's Disease. Six patients presented a decreased alpha band coherence, more prounounced over temporo-parietal region in 3 patients and in frontal region in other 2 patients. In 2 out of these 6 patients, there was a significant increase of delta coherence, without phase shift, more pronounced over regions far from the examined electrode. These two changes are probably related to different pathophysiologic events: alpha coherence decrease is due to alterations of cortico-cortical connections while delta coherence increase is secondary to the involvement of cholinergic pathways projecting diffusely to cortical areas.