The aging population: implications for the burden of neurologic disease

The aging population has had a significant impact upon the societal burden of several neurologic disorders, such as Alzheimer's disease, primary malignant brain tumor, Parkinson's disease, and amyotrophic lateral sclerosis. The increased burden is the result of more than just the dramatically increasing number of elderly individuals. This profound demographic change in the age structure of populations in developed nations is primarily the result of increasing survival. This differential survival over time, and its corresponding less selective culling effect on the surviving population gene pool, is an additional explanation for the observed increasing frequency of several neurologic diseases associated with senescence.