The EEG as a diagnostic tool in distinguishing between dementia with Lewy bodies and Alzheimer’s disease
Introduction
Dementia with Lewy bodies (DLB) is widely considered to be the second most common cause of degenerative dementia after Alzheimer’s disease (AD). The core features are fluctuating cognition, recurrent visual hallucinations and parkinsonism. In 2005 consensus criteria for the diagnosis of DLB were revised to improve diagnostic accuracy (McKeith et al., 2005). However the diagnosis of DLB is still mostly based on the clinical picture and not all of the core features may be present at initial presentation or even during the entire course of the disease making it challenging to discriminate DLB from other dementias, especially AD, the most frequent clinical misdiagnosis of DLB. There are limited ancillary investigations to aid in the diagnostic process. The only test with high diagnostic accuracy is reduced striatal dopamine transporter uptake on functional imaging with a sensitivity of 78% and a specificity of 90% and is considered a suggestive feature for the diagnosis of DLB (Walker et al., 1999, Walker et al., 2002, McKeith et al., 2007). However this diagnostic test is not widely accessible for clinical use and alternative methods to improve accuracy of the diagnosis of DLB are needed.
In most memory clinics the electroencephalogram (EEG) is not considered a standard tool in the diagnostic workup of patients with DLB. Although quantitative EEG analysis have shown promise (Walker et al., 2000, Kai et al., 2005, Bonanni et al., 2008), this is a time consuming tool and not readily accessible for daily clinical practice. In the evaluation of dementia visual EEG analysis is only considered in case of suspected Creutzfeldt–Jacob disease, metabolic encephalopathy or non-convulsive seizures, or to differentiate AD from depression (Jonkman, 1997). There are reports that suggest that EEG abnormalities are more severe in patients with DLB compared to patients with AD reflecting the more severe loss of acetylcholine (Perry et al., 1993, Briel et al., 1999, Franciotti et al., 2006). However studies comparing EEG of patients with DLB and AD are scarce and conflicting as some report no differences between these two groups (Barber et al., 2000, Londos et al., 2003). In part this could be due to the use of different EEG scoring methods.
The Grand Total EEG score (GTE) is a qualitative EEG analysis method and has proven its diagnostic value in a variety of AD studies (Jonkman, 1997, Strijers et al., 1997, Claus et al., 1999). Only one study has compared the GTE scores of patients with DLB and AD (Roks et al., 2008). This study reported a significantly higher GTE score in patients with DLB and a good sensitivity and specificity to differentiate DLB from AD. Until this date however, these results have never been validated. In the present study we test the reproducibility of the former study. In addition, the present study was conducted in a different setting i.e. general teaching hospital compared to a tertiary referral clinic in the former study. Our goal is to determine the usefulness of the GTE score in daily clinical practice as an additional tool in the diagnostic workup and in the differentiation between patients with DLB and AD.
Section snippets
Patients
29 patients with probable DLB according to the consensus diagnostic guidelines (McKeith et al., 2005) were selected from the database of the memory outpatient clinic of St. Elisabeth Ziekenhuis, a general teaching hospital in Tilburg in the Netherlands. Of the 29 DLB patients there were 8 with 3 core features and 18 with 2 core features. The remaining 3 DLB patients had 1 core feature of which 2 had 2 additional suggestive features, and 1 had 1 additional suggestive and 1 supportive feature.
Results
Baseline clinical characteristics are given in Table 1. Groups were well matched for age and gender. The degree of cognitive impairment was comparable between the DLB and AD group as measured by the MMSE.
Total GTE scores and subscores are given in Table 2. The DLB group had a significantly higher total GTE score compared to the AD group (p < 0.001). Logistic regression revealed that a single point increase on the GTE score resulted in a 1.3-fold increased risk (95% CI 1.1–1.5) for DLB. Corrected
Discussion
It has been suggested that loss of acetylcholine is responsible for the EEG abnormalities in AD, possibly related to the atrophy of basal forebrain cholinergic neurons, which innervate the neocortex and hippocampus (Dringenberg, 2000). This hypothesis is supported by reports of improvement of EEG background rhythm in patients with AD after treatment with cholinesterase inhibitors (Shigeta et al., 1993, Adler and Brassen, 2001, Brassen and Adler, 2003). Several studies show that EEG
Conflict of interest
None of the authors have potential conflicts of interest or financial interest to be disclosed.
References (26)
- et al.
Clinical neurophysiology in the diagnosis of Alzheimer’s disease
Clin Neurol Neurosurg
(1994) Alzheimer’s disease: more than a ‘cholinergic disorder’ – evidence that cholinergic–monoaminergic interactions contribute to EEG slowing and dementia
Behav Brain Res
(2000)- et al.
Cortical rhythms reactivity in AD, LBD and normal subjects: a quantitative MEG study
Neurobiol Aging
(2006) EEG dynamics in patients with Alzheimer’s disease
Clin Neurophysiol
(2004)The role of the electroencephalogram in the diagnosis of dementia of the Alzheimer type: an attempt at technology assessment
Neurophysiol Clin
(1997)- et al.
Quantitative electroencephalogram analysis in dementia with Lewy bodies and Alzheimer’s disease
J Neurol Sci
(2005) - et al.
Regional cerebral blood flow and EEG in clinically diagnosed dementia with Lewy bodies and Alzheimer’s disease
Arch Gerontol Geriatr
(2003) - et al.
Sensitivity and specificity of dopamine transporter imaging with 123I-FP-CIT SPECT in dementia with Lewy bodies: a phase III, multicentre study
Lancet Neurol
(2007) - et al.
In-vivo demonstration of dopaminergic degeneration in dementia with Lewy bodies
Lancet
(1999) - et al.
Short-term rivastigmine treatment reduces EEG slow-wave power in Alzheimer patients
Neuropsychobiology
(2001)
The electroencephalogram in dementia with Lewy bodies
Acta Neurol Scand
EEG comparisons in early Alzheimer’s disease, dementia with Lewy bodies and Parkinson’s disease with dementia patients with a 2-year follow-up
Brain
Short-term effects of acetylcholinesterase inhibitor treatment on EEG and memory performance in Alzheimer patients: an open, controlled trial
Pharmacopsychiatry
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