Brain electrical activity (quantitative EEG and bit-mapping neurocognitive CNV components), psychometrics and clinical findings in presenile subjects with initial mild cognitive decline or probable Alzheimer-type dementia

Abstract

Clinical, neuropsychological and neuropsychophysiological data (Q-EEG, ERPs and CNV/RT activity) were obtained from 24 patients who had more or less severe presenile primary cognitive decline without depression, and compared with similar data from 10 age-matched healthy volunteers (mean age, 59.4 years). All of the patients (15 M and 9 F; mean age 59.6 years) were selected according to the DSM III-R, ICD-10 and NINCDS-ADRDA criteria and underwent CT and MRI scanning, in addition to a standard clinical examination, a battery of psychometric tests, spectral EEG, and bit-mapped CNV complex and RT to S2 analyses. Twelve of the 24 patients presented an initial presenile idiopathic cognitive decline (PICD) but did not wholly fulfil the clinical and neuropsychological criteria for primary dementia or for a diagnosis of probable AD; the remaining 12 patients showed characteristic clinical signs and symptoms of a very probable early stage of presenile Alzheimer-type dementia (PAD). ANOVA, correlational and discriminant analyses of the neuropsychological test scores, and the neurophysiological and RT to S2 data revealed 22 highest-ranked between-group discriminant factors (all with a significance level of p < 0.01). The conclusive discriminant analysis retained 13 of these factors as final canonical functions, and these showed a 97% grouping accuracy (33 of the 34 subjects examined); the same percentage of correct classifications was also achieved using only the 15 best indicators in the group of CNV/RT findings. Using both of these sets of highest-ranked discriminators, all of the normal subjects and all of the PAD patients were correctly classified; only 1 PICD patient was misclassified as normal when the first group of 13 factors was used, and another PICD patient was misclassified as PAD using the second group of 15 factors. Our findings suggest that, providing they are correctly performed and interpreted, these non-invasive techniques may be an important tool for identifying incipient stages of presenile Alzheimer-type dementia.

Hippocampal atrophy and EEG markers in subjects with mild cognitive impairment

“…Recent postmortem data from subjects -who had been prospectively followed and clinically characterized up to immediately before their death -indicate that hippocampal choline acetyltransferase levels are reduced in Alzheimer's dementia, but in fact they are upregulated in MCI (Lavenex and Amaral, 2000;DeKosky et al, 2002), presumably because of reactive upregulations of the enzyme activity in the unaffected hippocampal cholinergic axons. Previous EEG studies (Babiloni et al, 2000;Jelic et al, 2000Jelic et al, , 1996Ferreri et al, 2003) have shown a decrease -ranging from 8 to 10.5 Hz (low alpha) -of the alpha frequency power band in MCI subjects, when compared to normal elderly controls (Zappoli et al, 1995;Huang et al, 2000;Jelic et al, 2000;Koenig et al, 2005;Babiloni et al, 2006a). However, a recent study has shown an increase -ranging from 10.5 to 13 Hz (high alpha) -of the alpha frequency power band, on the occipital region in MCI subjects, when compared to normal elderly and AD patients (Babiloni et al, 2006a).…”

Vascular damage and EEG markers in subjects with mild cognitive impairment

“…The quantitative analysis of electroencephalographic (EEG) rhythms in resting subjects is a low-cost but still powerful approach to the study of elderly subjects in normal aging, MCI and dementia (Gueguen et al, 1991;Maurer and Dierks, 1992;Leuchter et al, 1993;Schreiter-Gasser et al, 1993;Zappoli et al, 1995;Jelic et al, 1996Jelic et al, , 2000Huang et al, 2000;Bennys et al, 2001;Koenig et al, 2005;Babiloni et al, 2006a,b;Prichep et al, 2006;Rossini et al, 2006). The anchor point for a quantitative analysis of the EEG is the a rhythm, which dominates the EEG power spectrum in resting, awake and healthy subjects (Elul, 1972;Lopes da Silva et al, 1976Steriade and Llinas, 1988;Singer, 1993;Destexhe and Sejnowski, 1996;Klimesch, 1997Klimesch, , 1999Pfurtscheller and Lopes da Silva, 1999;Nunez et al, 2001;Suffczynski et al, 2001;Klimesch et al, 2007).…”

Decreased Theta Event-Related Synchronization during Working Memory Activation Is Associated with Progressive Mild Cognitive Impairment

“…In terms of MCI conversion to AD, two longitudinal studies proposed various quantitative EEG parameters for an a priori distinction between PMCI and stable MCI (SMCI) [13,14] . However, cross-sectional comparisons revealed a substantial overlap in these parameters between MCI patients and elderly controls [10,11,14,17] . Methodological differences including variable clinical definition of MCI cases and substantial interindividual differences within the MCI group could partly explain these discrepancies.…”

“…In this context, electroencephalography (EEG) is an easily accessible and low-cost modality that might prove to be a particularly powerful tool for the identification of subtle functional changes preceding structural or metabolic deficits in PMCI. Most previous contributions in this field assessed quantitative EEG differences between healthy controls, MCI and AD cases leading to contradictory data [9][10][11][12][13][14][15][16][17] . In terms of MCI conversion to AD, two longitudinal studies proposed various quantitative EEG parameters for an a priori distinction between PMCI and stable MCI (SMCI) [13,14] .…”