The EEG as a diagnostic tool in distinguishing between dementia with Lewy bodies and Alzheimer's disease

Abstract

Objective: Current diagnostic criteria for dementia with Lewy bodies (DLB) regard electroencephalogram (EEG) abnormalities as a supportive feature. It has also been suggested that EEG abnormalities in DLB are more extensive than in Alzheimer's disease (AD). Still, the use of qualitative EEG analysis as a diagnostic tool to distinguish between DLB and AD remains rare in daily clinical practice because of conflicting studies and absence of a reliable scoring method. The Grand Total EEG (GTE) score has been used in one study to differentiate DLB from AD with good sensitivity and specificity (Roks et al., 2008).

Methods: EEGs from 29 patients with DLB and 54 with AD were visually rated according to the GTE score.

Results: Patients with DLB had significantly higher median scores than patients with AD: 9 vs. 4. Patients with DLB could be distinguished from those with AD at a GTE cut-off score of 6.5 with a sensitivity of 79% and a specificity of 76%. The association between GTE and DLB was independent of age, gender, Mini Mental State Examination and use of medication. Frontal intermittent rhythmic delta activity (FIRDA) was found in 17.2% of patients with DLB compared to 1.8% with AD. Except for the lower cut-off score our results are comparable to the previous study on the GTE score.

Conclusion: The GTE score has proven to be a reliable and simple scoring method applicable to daily clinical practice. Qualitative EEG analysis can help to differentiate DLB from AD with good sensitivity and specificity.

Significance: EEG should play a more prominent role in daily clinical practice as a diagnostic tool in differentiating DLB from AD. Future revisions of the diagnostic criteria for DLB should consider the other EEG abnormalities as mentioned in the GTE score, especially FIRDA.

Keywords: Alzheimer’s disease; Clinical neurophysiology; Dementia; EEG; Lewy body.