Quantitative Electroencephalography and Regional Cerebral Blood Flow: Discriminant Analysis between Alzheimer’s Patients and Healthy Controls

Abstract

Forty-two patients with probable Alzheimer’s disease (AD) and 18 elderly healthy controls underwent quantitative EEG (qEEG) and regional cerebral blood flow (rCBF; ¹³³Xe clearance) examinations. Correlations were sought between relative qEEG band powers and percent rCBF values in a posterior temporoparietal region of interest in either hemisphere. Moreover, stepwise discriminant analysis was applied to study the accuracy of the two techniques in differentiating AD from healthy ageing. rCBF and qEEG were correlated with one another, especially in the right hemisphere (p values ranging from <0.001 to <0.01). Significant correlations were found between Mini Mental State Examination (MMSE) and relative power of both the 2- to 6-Hz and the 6.5- to 12-Hz bands on either side (p < 0.001), and between MMSE and left rCBF (p < 0.005), while the correlation with right rCBF was poorer (p < 0.02). The statistical procedure identified the right values of both examinations for the discriminant analysis. Sensitivity of qEEG and rCBF employed together was 88% and specificity 89%, with a total accuracy of 88.3%. The unrecognized patients (n = 5) were affected by mild AD (4 scoring 3 at the Global Deterioration Scale and 1 scoring 4). qEEG alone showed an accuracy of 77% in the whole group and of 69% in mild AD, and rCBF alone an accuracy of 75% in the whole group and of 71% in mild AD. It is concluded that qEEG and rCBF examinations employed together are accurate tools to differentiate AD from normal ageing, although a lower degree of accuracy is achieved in mildly demented patients.

Slowing of EEG correlates with CSF biomarkers and reduced cognitive speed in elderly with normal cognition over 4 years

“…The possible involvement of hippocampus is further supported by the correlation of medial temporal lobe atrophy and increase in neocortical theta activity in human studies [21]. Another mechanism associated with slowing of the EEG is progressive cortical hypoperfusion [36,46], where disturbed connections in autoregulation or regulation from deeper areas on vessels could be a possible contributor.…”

“…Hippocampal atrophy on MRI [21], abnormal cerebral blood flow [36,46], autopsy-confirmed neuron loss [45], activity of daily living functions [39] and memory function [44,57] have all correlated with slowing of EEG rhythm. Furthermore, a previous study reported a correlation between tau protein and slowing of EEG global field 5 power in a healthy control group [28].…”

Regional Cerebral Blood Flow and Prognostic Evaluation in Alzheimer’s Disease

“…Recent data [39] comparing rates of glucose metabolism with that of [ 11 C]methionine accumulation, as measured by PET, support the view that tissue loss alone cannot explain the glucose hypometabolism of AD patients, which may actually reflect reduced synaptic activity at least in part. By reflecting tissue loss and probably synaptic dysfunction as well, metabolic and blood flow measurements are significantly related to the severity of the disease [21,40,41] and then may be expected to be linked with disease progression as well.…”

“…There were 69 women and 32 men, aged 45-91 years (mean 70.1 B 8.7 years) with apparent duration of disease (determined as onset of first symptoms referred by the patient or his/her relatives) ranging from 6 to 108 months (mean 32.1 B 24 months). All patients underwent a complete diagnostic workup according to the current clinical standards, as already described in detail elsewhere [21]. Consistent with the diagnosis of AD, all of them scored lower than 4 on the modified Hachinski Ischemic Scale.…”

“…The O1 probe is positioned at the level of the temporo-occipital junction, thus recording counts from the posterior temporal and from the most anterior portion of the superficial occipital region, the latter being often involved by the disease process as well [29][30][31][32]. Moreover, this area was already shown in previous studies to have the lowest CBF levels in AD patients as compared to healthy controls [21,33]. In the text, the area is referred as 'PT-IP' (posterior temporal-inferior parietal).…”