Slow-wave activity in the spectral analysis of the electroencephalogram and volumes of hippocampus in subgroups of Alzheimer's disease patients.

Abstract

This study examined patients who fulfilled the National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association Work Group criteria for probable Alzheimer's disease (AD; n = 35) and controls for magnetic resonance imaging and psychometric data (n = 16) and for quantitative electroencephalogram data (n = 34). A cluster analysis performed on neuropsychological variables identified 2 AD subgroups: The AD1 group (n = 12) had impaired memory and executive functions but preserved verbal and visuospatial functions. The AD2 group (n = 23) had global impairment. The AD2 group had higher theta amplitude in the temporo-occipital, centroparietal, and frontal derivation and lower peak and mean frequency than the AD1 group or controls. Both AD groups had more severe memory deficits and clearly smaller hippocampal volumes than controls. This may implicate that the degree of damage in ascending activating systems differs in these subgroups, although the damage in the hippocampus is equal.

Spectral analysis of wakefulness and REM sleep EEG in patients with sleep apnoea syndrome

“…However, REM sleep EEG was also sampled outside apnoea episodes in three patients and the results showed an increase in the δθ/αβ ratio (1.49±0. 19) similar to that seen in REM sleep EEG during apnoeas (1.59±0.27). No correlation was found between REM sleep EEG slowing and degree of oxygen desaturation (time with Sa,O 2 <90%).…”

“…Quantitative electroencephalographic analysis (qEEG) was used to assess potential frontal lobe dysfunction in OSAS patients. The qEEG has been found to be useful in the classification of vascular and degenerative dementia [16][17][18][19][20].…”

A Longitudinal Quantitative EEG Study of Alzheimer’s Disease: Relation to Apolipoprotein E Polymorphism

“…We also examined 34 age-and sex-matched control subjects who participated in an epidemiological study on the prevalence of dementia. They had undergone clinical examination, neuropsychological tests, QEEG and brain MRI [26]. The QEEG values of the control subjects were the same at baseline and follow-up because, in a previous 2-year EEG study, there were no changes in the various bands for normal subjects; further, no increase in EEG slowwave activity with age was indicated (age groups 20-39, 40-59 and 60-91 years).…”

A New Method for Quantification and Assessment of Epileptiform Activity in EEG with Special Reference to Focal Nocturnal Epileptiform Activity

“…The alpha rhythm is also prone to frequency changes in some disorders as epilepsy, dementia and some tumours, and in treatment with antiepileptic drugs [27][28][29][30][31][32][33][34][35] to some extent implemented to find alpha rhythm frequencies in short segments (a few seconds), but fully automatic analysis is not commonly applied clinically.…”

“…Peak-to-peak intervals outside the alpha band (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36) Hz (period time: 0.0781s -0.1406s)) and peaks with amplitude difference below 10 ȝV in two consecutive half waves were discarded.…”