Timing of Disease Progression by Quantitative EEG in Alzheimer’s Patients

Abstract

This prospective study was planned to assess whether quantitative EEG (qEEG) can give an estimate of the timing of achievement of three endpoints (loss of activities of daily living, incontinence, and death) in 72 consecutive patients (53 females, 19 males; mean age, 70.8) affected with probable Alzheimer's disease, as defined according to the NINCDS-ADRDA criteria. Power-weighted, log-transformed relative values of the four conventional EEG bands were considered in a central-posterior temporal region for each hemisphere. The hypothesis was tested by the lifereg procedure of the Statistical Analysis System package (first significance level accepted, P < or = 0.01). Because patients were in different stages of the disease, the statistical analysis was performed in the entire group as well as in the subgroup of 41 patients (mean age, 69.6) with mild dementia (scoring 3 or 4 on the global deterioration scale). In the whole group, the loss of activities of daily living was predicted by delta power in either side (P = 0.01), incontinence was predicted by alpha power in the right side (P < 0.01), whereas the statistical significance was not reached for death (P < 0.05). In the subgroup of mild demented patients, the loss of activities of daily living was predicted by delta power in the left side (P = 0.01), incontinence by both delta (P < 0.01) and alpha (P < 0.001) power in the right side, and death was not significantly predicted (P = 0.08). Quantitative EEG is a low-cost, discomfort-free technique which may be used to obtain information on the timing of disease evolution. The results showed in mild Alzheimer's disease appear especially interesting to attempt a prediction of the future time course of the disease from its beginning.

Individual analysis of EEG frequency and band power in mild Alzheimer's disease

“…These findings agree with previous reports in which white matter lesions in mild VaD induced a large and widespread increase of the slow EEG power (Gloor et al, 1968;Coben et al, 1983), correlated with a reduction in regional cerebral metabolism (Szelies et al, 1999). The present findings also agree with previous studies in AD demonstrating an increase in slow EEG rhythms together with a reduction of regional cerebral blood flow (Rae-Grant et al, 1987;Stigsby et al, 1981;Brenner et al, 1986;Nobili et al, 1999).…”

“…Compared to normal subjects, Alzheimer's disease (AD) patients are known to have 'slowing of the EEG,' namely through increase of the delta (0.5 -4 Hz) and theta (4 -8 Hz) power, along with decrease of the alpha power (8 -13 Hz). 'Slowing' of the EEG rhythms may be sensitive and correlate to dementia severity and disease progression from the earliest stages (Schreiter-Gasser et al, 1994;Nobili et al, 1999;Ihl et al, 1996). These findings are considered indirect evidence of the fundamental role of cholinergic system in modulating alpha rhythms, given the well-known selective deficit of acetylcholine occurring from the earliest stages of AD.…”

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

“…On the other hand, neurophysiologic techniques have the potentiality of obtaining objective information on the pathophysiologic condition of brain areas at any stage of the disease, and therefore may potentially add useful prognostic information to the clinical clues. Conventional [12] and, more recently, quantitative electroencephalography (EEG) [10,[13][14][15][16] are giving promising results, while the few studies on regional cerebral blood flow (rCBF) [17,18] suggest a potential prognostic power of such an assessment.…”

EEG Pattern in Alzheimer’s Disease at Resting Condition

“…'Slowing' of the EEG rhythms may be sensitive and correlate to dementia severity and disease progression from the earliest stages [20,21] . These findings are considered indirect evidence of the fundamental role of cholinergic system in modulating alpha rhythms, given the well-known selective deficit of acetylcholine occurring from the earliest stages of AD.…”

“…Electrical brain activity has been described following a wave pattern consisting of different types of frequency bands, namely delta (0-4 Hz), theta (4-8 Hz), alpha (8-13Hz), beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and gamma (30-50Hz) waves [11] .In this context the present study was undertaken to explore neural dynamics as patterned through EEG rhythm and to appreciate an insight into the functioning of human mind in relation to cognitive decline.…”