QUANTIFICATION OF OCCIPITAL EEG CHANGES IN ALZHEIMERS-DISEASE UTILIZING A NEW METRIC - THE FRACTAL DIMENSION

In a retrospective preliminary investigation, the occipital electroenc ephalogram (EEG) changes associated with Alzheimer's disease (AD) were examined using a novel quantification metric: the fractal dimension. The mean occipital EEG fractal dimension was determined for each of th ree patient groups representing a spectrum of clinical and EEG patholo gy: controls, probable AD, and autopsy-confirmed AD. The fractal dimen sion was significantly reduced in each of the AD groups with respect t o controls (p < 0.001); and within the AD groups, it was significantly reduced in autopsy-confirmed AD relative to probable AD (p < 0.001). The fractal dimension findings paralleled the manifest EEG abnormaliti es in a way that suggests it has potential clinical utility in metric studies on the EEG, especially when applied to the dementias. Addition ally, the EEG pathology studied here was particularly well-described b y the fractal dimension, providing further support for a nonlinear app roach to the background activity of the EEG.