Electroencephalography and single photon emission computed tomography in dementia: a comparative study

Abstract

SYNOPSISA series of elderly patients with dementia of Alzheimer type (AD), multi-infarct dementia (MID) and functional (non-organic) psychiatric illness (major depressive disorder) were selected according to DSM-III-R criteria and received: a battery of cognitive tests, EEG and Single Photon Emission Computed Tomography (SPECT) using 99mTc HMPAO. The EEG and SPECT scans were examined independently of the clinical data. The former were divided into two abnormal categories, those showing AD type change and vascular change respectively, and a normal group. The SPECT scans were classified as follows: a SPECT rCBF pattern showing bilateral temporoparietal perfusion deficits (AD type); those showing single focal perfusion deficits or multiple areas of low perfusion in the cerebral cortex suggestive of ischaemic change (vascular type SPECT picture); a mixed AD/MID pattern; and those with normal scan findings. There were significant associations between clinical diagnosis, EEG rating and SPECT rCBF pattern, approximately three-quarters of AD and MID patients having the predicted EEG and scan changes. Normal EEG recordings were more common in the MID patients. The two tests agreed in about two-thirds of cases, with no consistent pattern apparent in the cases with divergent findings. Each test misclassified a minority of dementia patients, but in only one patient were both investigations normal. Almost half of the so called ‘functionally ill’ patients had abnormal rCBF changes, showing mainly vascular changes while one-fifth had abnormal EEGs.

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

“…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. However, the typical 'slowing' of EEG rhythms seen in AD (Coben et al, 1983(Coben et al, , 1990Sloan et al, 1995) has also been reported in vascular dementia (VaD; Szelies et al, 1992).…”

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

“…By discriminant analysis on qEEG and rCBF performed on the same sample of patients but considered in a separate analysis, sensitivity was shown to reach 77% for qEEG and 63% for perfusional SPECT, while specificity scored 93% for qEEG and 88% for SPECT [30]. In a qEEG/PET study on AD patients and normal controls, accuracy values of 86% for temporoparietal relative theta power and of 87% for rCMRGlu were reported, whereas in the mild AD subgroup the corresponding figures were 66.7 and 75% [12].…”

“…Moreover, even in the field of AD, some attempts have recently been made in order to assess the relationships between EEG and metabolism, and to evaluate whether these parameters may increase the ability to detect pathological changes even in most subtle cases [12,30].…”

Donepezil effects on sources of cortical rhythms in mild Alzheimer's disease: Responders vs. Non-Responders

“…AD patients were characterized by higher delta (0 -3 Hz), higher theta (4 -7 Hz), lower posterior alpha (8 -12 Hz), slowing in alpha peak frequency, and lower beta (14 -30 Hz) and gamma (around 40 Hz) (Dierks et al, 1993Huang et al, 2000;Wolf et al, 2003;Babiloni et al, 2004;Moretti et al, 2004;Adeli and GhoshDastidar, 2005). The abnormality of EEG rhythms in dementia has been associated with altered rCBF/metabolism and cognitive function (Szelies et al, 1992;Julin et al, 1995;Passero et al, 1995;Sloan et al, 1995;Rodriguez et al, 1999aRodriguez et al, , 1999b. Furthermore, parieto-temporal EEG rhythms and rCBF have been correlated with severity of AD as measured by Mini Mental State Evaluation scores (MMSE).…”