Figure 4.

Schematic representation of natural course of Alzheimer’s disease and importance of preemptive approach. Alzheimer’s disease develops through interactions of genetic and environmental factors. The role of perinatal environment is still not understood, but some cohort studies mentioned in the text showed that those who were exposed to adverse perinatal environment develop early decline of cognitive function, suggesting the possible involvement of fetal life. As environmental factors in adulthood, metabolic abnormalities such as type 2 diabetes become risk factors. It is possible to diagnose preclinical Alzheimer’s disease by some biomarkers or PET scanning, intervention before the onset of MCI will become the most important approach. In other words, preemptive medicine will become a standard approach for preventing Alzheimer’s disease.