Age acceleration can be defined as the difference between the DNA methylation age and the actual age, or as the residual resulting from regressing the DNA methylation age on the actual age. In comparison, the latter definition is more accurate and practical. We can determine the rate of biological aging based on the specific value of the DNA methylation age acceleration, with positive values indicating faster than expected aging and negative values the opposite.

DNA methylation age acceleration calculation is closely related to the health status of the organism, aging-related diseases, mortality and other factors. On the one hand, several studies have identified DNA methylation age acceleration in age-related diseases, such as cancer, cardiovascular diseases, and neurodegenerative diseases. On the other hand, there are also some intrinsic and extrinsic factors that contribute to age acceleration in individuals, such as stress, alcohol consumption, smoking, etc.