VOLUMETRIC ESTIMATES OF BRAIN ATROPHY AND QUANTITATIVE EEG IN NORMAL AGING AND ALZHEIMERS-DISEASE

We studied (1) the differences of volumetric estimates of brain atroph y in normal ageing and Alzheimer's disease (AD); (2) the correlation o f these estimates with age and cognitive performance; (3) the differen ces between absolute EEG power between ageing and AD; (4) the correlat ion between EEG power and age or cognitive performance; and (5) the co rrelation between volumetric and EEG data. 84 patients with a clinical diagnosis of AD and 45 age-approximated non-demented controls between 48 and 91 years of age were examined. For statistical comparisons the volumetric estimates of intracranial cerebrospinal fluid (csf) spaces were converted into percentages of total intracranial volume. The EEG was recorded from 17 locations at resting conditions, eyes closed, ac cording to the 10/20 system. Logtransformed absolute band powers were compared between the AD and control groups and correlated with clinica l and volumetric findings. The total intracranial csf-space, both late ral ventricles, the third ventricle, anterior, lateral and posterior f issures were significantly larger in AD than in non-demented controls. In normal ageing the csf-volumes were significantly correlated with a ge, whereas age and cognitive performance were differentially correlat ed with these variables in AD. In AD, the absolute delta or theta powe r was significantly higher in all locations, whereas alpha power was l ower than in normal controls. These differences were significantly cor related with cognitive performance. There were no significant correlat ions between the csf-volumes and EEG-power in AD and the control group with one exception: we found a significant in verse correlation betwe en the volumes of the anterior and posterior fissure and the alpha-1 a nd alpha-2 power independent of electrode location in AD. We conclude that the morphological and EEG-changes in AD are largely independent a nd suggest that the functional relationship between alpha-power and an terior or posterior fissure volume needs further examination.