Quantified electroencephalographic correlates of relative frontal or parietal hypoperfusion in dementia

Who's driving? The default mode network in healthy elderly individuals at risk of cognitive decline

Introduction

Age is the main risk factor for the development of neurocognitive disorders, with Alzheimer's disease being the most common. Its physiopathological features may develop decades before the onset of clinical symptoms. Quantitative electroencephalography (qEEG) is a promising and cost-effective tool for the prediction of cognitive decline in healthy older individuals that exhibit an excess of theta activity. The aim of the present study was to evaluate the feasibility of brain connectivity variable resolution electromagnetic tomography (BC-VARETA), a novel source localization algorithm, as a potential tool to assess brain connectivity with 19-channel recordings, which are common in clinical practice.

Methods

We explored differences in terms of functional connectivity among the nodes of the default mode network between two groups of healthy older participants, one of which exhibited an EEG marker of risk for cognitive decline.

Results

The risk group exhibited increased levels of delta, theta, and beta functional connectivity among nodes of the default mode network, as well as reversed directionality patterns of connectivity among nodes in every frequency band when compared to the control group.

Discussion

We propose that an ongoing pathological process may be underway in healthy elderly individuals with excess theta activity in their EEGs, which is further evidenced by changes in their connectivity patterns. BC-VARETA implemented on 19-channels EEG recordings appears to be a promising tool to detect dysfunctions at the connectivity level in clinical settings.

Describing brain activity of persons with AD and depressive symptoms

The purpose of this retrospective pilot study was to characterize depression of AD using electrophysiological changes in the brain activity of persons with AD and depressive symptoms. Participants had a mean age of 70.12±12.68. Participants manifested an increase in absolute/relative theta activity (p=.000) over entire brain when compared to normative population-based database. Electrophysiological changes did not differ by age or gender except for increased absolute theta activity in the right lateral frontal areas (t-test=-2.31 to -2.39, p=.04) in females. An increased theta activity suggests that depressive symptoms may be part of AD symptomatology, not a co-morbid feature.

The utility of EEG in dementia: a clinical perspective

BACKGROUND

Despite being simple and cheap, the EEG is not often used in clinical practice.

METHODOLOGY

Literature search using PUBMED and Medline.

RESULTS

Quantitative EEG can help to identify mild dementia and mild cognitive impairment and can increase diagnostic accuracy when used with other imaging techniques. EEG helps differentiate organic from functional brain disease and predict response to cholinesterase inhibitors and is central in the diagnosis of Creutzfeldt Jacob disease. The accuracy of EEG may be greater than that of CT or MRI scans alone.

DISCUSSION

Quantitative EEG may save on specialist interpretation time and enable more routine use of EEG in diagnosis and care. More widespread use of EEG's is indicated. Agreement on the parameters that are best measured on qEEG is still awaited.

EEG and the passive P300 in dementia of the Alzheimer type

Quantitatively analyzed resting electroencephalographic (EEG) activity and P300 event-related potentials elicited with a passive tone sequence paradigm were examined in 30 patients with dementia of the Alzheimer type (DAT) and 15 age matched controls. Background electrical rhythms of DAT patients evidenced slowing as shown by increased absolute and relative amplitudes in slow frequency bands and decreased amplitudes in fast frequency bands (relative to controls). Electrical slowing was more evident in patients with higher clinical ratings of global intellectual deterioration. Passive P300 amplitude and latency did not differentiate patients and controls and were not related to severity of dementia.