R. Ihl

Dementia of the alzheimer type: Effects on the spontaneous EEG described by dipole sources

The present study on brain electrical activity in healthy subjects (n = 35) and patients suffering from dementia of the Alzheimer type (DAT; n = 35) used Fast Fourier Transformation-dipole approximation to quantify differences between the two groups. DAT patients showed a shift of alpha and beta activity toward frontal brain regions. The amount of this shift correlated with the degree of dementia. The relative distribution of magnitude of activity between the frequency bands differed between DAT patients and control subjects. DAT patients had higher magnitudes in the slow frequency range, correlating with the severity of dementia, and lower ones in the alpha and beta range compared with findings in age-matched control subjects.

Topography of the quantitative electroencephalogram in dementia of the Alzheimer type : relation to severity of dementia

Conventional electroencephalographic (EEG) frequency bands and peak frequency were investigated in patients with probable dementia of the Alzheimer type (DAT). Measures of EEG topography and activity were also related to the severity of dementia, as assessed by neuropsychological tests. EEG activity measured in conventional frequency bands proved to be the most sensitive parameter for the quantitative differentiation of DAT, whereas the topography of peak frequency was the better qualitative discriminator between healthy subjects and DAT patients.

Stage-dependent reductions of regional cerebral blood flow measured by HMPAO-SPECT in dementia of Alzheimer type

In the present study, we used HMPAO-SPECT to examine the rCBF patterns in two subgroups (moderately and severely demented) of patients with DAT. Temporoparietal and frontal cerebral blood flow were compared between the two patient groups

Topography of the maximum of the amplitude of EEG frequency bands in dementia of the Alzheimer type

The localization of the maxima of activity of 36 patients with dementia of the Alzheimer type and 36 age-matched controls was calculated after Fourier transformation of EEG data in six frequency bands (4 Hz steps between 1 and 24 Hz). Patients were divided into three groups of severity (BCRS mean < 3,9, 4.0-4.9, and > 4.9). Significant differences were found in the beta frequency band. In the distribution of the maxima of the activity, the maxima of patients were located more frontally than the maxima of controls. The alterations were staged dependent. The beta activity in EEG is said to be correlated with cognitive processes; the correlation between cognitive decline and decreasing beta activity in dementia of the Alzheimer type might support this assumption. Differences in the location of the maxima between patients and controls might allow for differentiation between both groups.

Staging in dementia of the alzheimer type: Topography of electrical brain activity reflects the severity of the disease

In dementia of the Alzheimer type (DAT), electrical brain activity shows increases in delta and theta frequencies as well as a diminution of beta frequency. Two groups of 10 patients, each suffering from DAT, were compared with 10 healthy aged controls with respect to topogaphy of beta activity

Electrical brain activity and cerebral blood flow in dementia of the Alzheimer type

Regional alterations in the distribution of beta activity over the scalp have not been investigated. Regional cerebral blood flow measured by HMPAO-SPECT is also able to detect DAT-related flow reductions in parietotemproal regions. Both measures were investigated to uncover regional effects of DAT

EEG and EP Mapping in Patients with Senile Dementia of Alzheimer Type Before and After Treatment with Pyritinol

The electroencephalogram (EEG) and evoked potentials (EP) show changes in electrical brain activity both in physiological aging and in senile dementia of the Alzheimer type (SDAT). In physiological aging there is slowing of the main alpha frequency in the order of 0.5–1 Hz (Visser 1985). In addition, an increase of beta activity from 12% in young adults to 24% in aged persons and an increase of slow activity from 7% to 15% can be observed. In SDAT the slowing of the alpha rhythm can be in the range of 1–3 Hz, so that an alpha frequency of 8 Hz and less is achieved. The amount of theta and delta activity can rise considerably (Gordon and Sim 1967). Focal lesions are not common in SDAT but are frequent findings in dementia due to multiple infarction (MID).

Topographic mapping of pharmaco-EEG before and after application of phosphatidylserine

As a means of obtaining information on the CNS action of psychotropic drugs, we studied the topographic distribution of brain electrical activity before and after administration of phosphatidylserine in normal volunteers

The effect of pyritinol upon P300 topography

The time course of information processing and parts of cognitive functioning can be measured objectively by means of exogenous and endogenous evoked potentials. The aim of the present investigation was to find out whether pyritinol, suggested in some experiments to enhance cognitive activity, has an effect upon allocortical functioning measured by means of P300 maps

Brain mapping of EEG and evoked Potentials during physiological aging and in Parkinson’s disease, dementia and depression

Electrical brain activity measured by topographical EEG and evoked potential (EP) recording was analyzed in 33 patients (suffering from dementia of Alzheimer type (10 DAT), parkinsons disease (13 PD) and depression (10 MDD) and 20 controls. P 300 in EP and four frequency bands in EEG (delta 0–3.5 Hz, theta 4–7.5 Hz, alpha 8–11.5 Hz, beta 12–15.5 Hz) were evaluated with statistical probability mapping.