Quantitative measurement of delta activity in Alzheimer's disease.

Quantitative measurements of delta activity were made in 10 healthy elderly controls and 31 subjects with Alzheimer's disease. Delta activity did not discriminate between the healthy elderly controls and the early mild Alzheimer's disease subjects. However, delta activity was a significantly greater percentage of total EEG power in the moderate-to-advanced Alzheimer's subjects when compared to either the healthy controls or mild Alzheimer subjects. In the T3 and T4 electrodes, delta activity in the moderate-to-advanced Alzheimer subjects was 78.3% and 47.6% higher, respectively, than in control subjects. Furthermore, delta activity was an excellent predictor of dementia severity within the 31 subjects with Alzheimer's disease.