Slowing and Loss of Complexity in Alzheimer's EEG: Two Sides of the Same Coin?

Table 1

Overview of statistical measures: relative power, Lempel-Ziv complexity, and lossless compression ratio.

Measure	Description	References
Relative power	Power within specific EEG frequency band normalized by total power	[12]
	Frequency bands: 0.5–4 Hz (delta), 4–8 Hz (theta), 8–10 Hz (alpha 1), 10–12 Hz (alpha 2), 12–30 Hz (beta)
Lempel-Ziv complexity	Number of different patterns present in an EEG signal (complexity measure)	[13]
Lossless compression ratio	Reduction of the size of EEG data after lossless compression (regularity measure)	[14, 15]
	Compression algorithms considered here: 1D SPIHT, 2D SPIHT, and 2D SPIHT followed by arithmetic coding