Power spectral density and lempel-ziv complexity analysis of EEG in Alzheimer's disease

To study the electroencephalograph (EEG) background activity in patients with Alzheimer's disease (AD), power spectrum density estimated by AR model and Lempel-Ziv (LZ) complexity are employed. EEG signals are recorded with 16-channel scalp electrodes in 15 patients with probable AD and 15 age-matched normal control subjects, in a relax state with eyes closed. Analysis results demonstrate that both relative PSD and LZ complexity of AD patients are increased in theta band and decreased in alpha band when compared with controls. Furthermore, specific to a particular frequency band, the topographical distribution of relative PSD and LZ complexity in the brain are matched. These preliminary results suggest that cognitive dysfunction in AD is associated with slowed power and decreased complexity in certain regions of the brain, though which we could differentiate AD patients from control subjects.