Key result
Alzheimer's disease was associated with significantly lower Lempel-Ziv complexity in magnetoencephalogram signals compared to controls (p<0.01), with a diagnostic AUC of 0.9002.
Why the study?
Does Lempel-Ziv complexity analysis of MEG signals differentiate Alzheimer's disease patients from age-matched controls?
Case-Control (n=42)
Does Lempel-Ziv complexity analysis of MEG signals differentiate Alzheimer's disease patients from age-matched controls?
Effect estimate: AUC 0.9002
p-value: p=<0.01
Lempel-Ziv complexity analysis of MEG signals shows high sensitivity and specificity in distinguishing Alzheimer's disease patients from healthy controls.
May support MEG complexity as AD biomarker; leaves open prospective validation before clinical adoption.
The aim of the present study was to analyse the magnetoencephalogram (MEG) background activity in patients with Alzheimer's disease (AD) using the Lempel-Ziv (LZ) complexity. This non-linear method measures the complexity of finite sequences and is related to the number of distinct substrings and the rate of their occurrence along the sequence. The MEGs were recorded with a 148-channel whole-head magnetometer (MAGNES 2500 WH, 4D Neuroimaging) in 21 patients with AD and in 21 age-matched control subjects. Artefact-free epochs were selected for complexity analysis. Results showed that MEG signals from AD patients had lower complexity than control subjects' MEGs and the differences were statistically significant (p<0.01). In order to reduce the dimension of the LZ complexity results, a principal components analysis (PCA) was applied, and only the first principal component was retained. The first component score from PCA was graphically analysed using a box plot and a receiver-operating characteristic (ROC) curve. A specificity of 85.71%, a sensitivity of 80.95% and an area under the ROC curve of 0.9002 were obtained. These preliminary results suggest that cognitive dysfunction in AD is associated with a decreased LZ complexity in the MEG signals.
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Gómez et al. (2006) conducted a case-control in Alzheimer's disease (n=42). Alzheimer's disease vs. Age-matched control subjects was evaluated on Lempel-Ziv (LZ) complexity of MEG signals (AUC 0.9002, p=<0.01). Alzheimer's disease was associated with significantly lower Lempel-Ziv complexity in magnetoencephalogram signals compared to controls (p<0.01), with a diagnostic AUC of 0.9002.
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