Nonlinear analysis of brain magnetoencephalographic activity in Alzheimer disease patients

Objectives: Non-linear analysis was applied on MEG signals of Alzheimer Disease (AD) patients in order to investigate the underlying complexity of the brain dynamics. Materials & methods: A Single channel SQUID was used to record the MEG signals in 9 AD patients and 5 normal individuals. The magnetic activity, for each patient, was recorded from a total of 64 points of the skull (32 points from each temporal lobe). Nonlinear analysis was applied in the abnormal MEG points of the brain. Results : In AD patients some recorded points were found with high amplitudes and low frequencies in magnetic activity. By applying nonlinear analysis in these records low values in the correlation dimension D of the reconstructed phase space were found. Conclusions: SQUID obtained MEG signaling from brains of AD patients showed a lower complexity compared to the brain of normal subjects.