In normal aging and Alzheimer's disease, there are regular changes in brain energy homeostasis, which are associated both with the time course of the average level of catabolism and with the intensity rate of catabolic processes by hemispheres. In normal aging, there is generally decrease in the catabolic level estimated by the level of the DC potential. In Alzheimer's disease, the level of catabolism secondarily increases. The findings suggest that there is a causal relationship between the brain energetic homeostasis and the visual information processes. The correlation of energetic and information processes increases with normal and especially pathological aging. The authors' methods enabled them to observe the time course of energy metabolism and to reveal their critical levels. The correction of energetic processes in due time should be useful in preventing atrophic changes in the brain with aging.