Determinants of quantitative spectral electroencephalography in early Alzheimer's disease: Cognitive function, regional cerebral blood flow, and computed tomography

Electroencephalography (EEG) bands may have different clinical or physiolog ical correlates at initial diagnosis of Alzheimer's disease (AD). We studie d 163 consecutive patients with probable (n = 105) and possible (n = 58) AD with measurements of cognitive function (CAMCOG), regional cerebral blood flow (rCBF) with single photon emission computed tomography using technetiu m-99m-labeled hexamethylpropylene amine oxime, and computed tomography (CT) , Lower CAMCOG scores were significantly and most strongly associated with lower parieto-occipital and fronto-central alpha power. In a separate analy sis of cognitive domains, disturbances in language, praxis, attention, and abstraction were also significantly and most consistently related to decrea se in alpha power. Presence of cortical atrophy as measured on CT showed so me statistically significant relations with EEG bands, but these associatio ns were not consistent. Lower temporal and parietal rCBF were significantly related to lower parieto-occipital alpha activity. Presence of leukoaraios is was significantly associated with lower beta values, but also with highe r absolute theta and delta activity. The results suggest that alpha on EEG is most closely linked to cognitive function and rCBF, while beta and theta activity more likely reflect lower cortical or subcortical changes. Our st udy thus provides evidence that the EEG bands reflect differential pathophy siologic changes in AD. Copyright (C) 2000 S. Karger AG, Basel.