Search

Abstract: Clinicopathophysiological differences between dementia with Lewy bodies (DLB) and Alzheimer''s disease (AD) remain obscure. Our goals were to determine whether characteristic findings of electroencephalogram (EEG) power and coherence in DLB and a differential pathophysiological mechanism of quantitative EEG existed between DLB and AD. The group consisted of 15 patients with AD or DLB and 12 age-matched controls. Original EEG signals were recorded from 14 scalp electrodes positioned according to the International 10-20 System, using digitally linked earlobes as a reference. Although EEG power spectral analysis showed increasing EEG power density in patients with DLB in the delta and theta bands, such a difference did not exist in patients with AD. Compared with AD, the delta and theta band intrahemispheric coherence values in the fronto-temporo-central regions were higher in DLB. In the beta band, AD was lower than DLB in almost all temporo-centro-parieto-occipital regions. Comparing the mean power value between patients with/without donepezil treatment, there was a significantly lower EEG power density in the delta and theta bands in DLB subjects taking donepezil than in subjects not taking donepezil, whereas there was no significant difference in AD patients. These results suggest that cholinergic dysfunction is stronger in DLB than AD. [Copyright &y& Elsevier]

Head-down tilt (HDT) causes a fluid shift towards the upper body, which increases intracranial pressure (ICP). In the present study, the time course of ICP changes during prolonged exposure to HDT was investigated in conscious rabbits through a catheter chronically implanted into the subarachnoid space. The production of cerebrospinal fluid (CSF) after exposure to 7-days HDT was also examined by a ventriculo-cisternal perfusion method. The ICP increased from 4.3±0.4 (mean±S.E.M.) mmHg to 8.0±0.8 mmHg immediately after the onset of 45° HDT, reached a peak value of 15.8±1.9 mmHg at 11 h, and then decreased to 10.4±1.1 mmHg at 24 h. During 7-days HDT, it also increased from 4.8±0.9 mmHg to 9.2±1.6 mmHg immediately after the onset of 45° HDT, reached a peak value of 12.8±2.5 mmHg at 12 h of HDT, and then decreased gradually towards the pre-HDT baseline value for 7 days. The rate of CSF production was 10.1±0.6 μl/min in rabbits exposed to 7-days HDT, and 9.7±0.5 μl/min in control rabbits. These results suggest that the rabbits begin to adapt to HDT within a few days and that the production of CSF is preserved after exposure to 7-days HDT. The time course of ICP changes during HDT in conscious rabbits seems to be considerably different from that in anesthetized rabbits. [Copyright &y& Elsevier]