The purpose of this study was to evaluate electroencephalogram (EEG) changes in various stages of dementia of the Alzheimer's type (DAT) through comparison with normal persons of the same age and gender. The study included 20 patients with DAT in four cognitive stages as defined by the Global Deterioration Scale (GDS) and a control group of 20 age- and gender-matched individuals without DAT. The EEGs were recorded using a Grass Model C7 Polygraph instrument and analyzed for number of alpha, beta, delta and theta waves in four leads. Statistical analysis included two-way analysis of variance (ANOVA), multiple linear regression and profile analysis. Alpha and theta waves were significant when comparing persons with DAT and control participants (p=0.05). Delta waves were significant for group, gender and lead placement (p=0.012). Linear regression showed a high significance between cognitive stage of the participant and alpha (p=0.000), theta (p=0.000) and delta (p=0.005) waves.