As with other bodily organ systems, brain function declines with age. Many older people notice changes in memory, learning, or other cognitive performance. These changes are associated with loss of neurons, the basic operative cells of the brain. The extent of “normal” brain aging varies among individuals and can be somewhat difficult to quantify. With “abnormal” brain aging, however, cognitive losses are typically more severe, and after the individual dies, significant pathological changes related to underlying disease processes are usually found in the brain at autopsy. The early identification of people at risk for abnormal brain aging is the subject of intense ongoing research on genetic, biochemical, and neuropsychological aspects of the transition from normal to pathologic aging.
Standardized neuropsychological tests have been developed and validated with consensus thresholds of abnormal performance that aid clinicians in evaluating mild cognitive impairment and dementia. The development of drug therapies or behavioral modifications to slow or possibly halt the complex processes involved in cognitive decline requires the earliest possible intervention. Hence researchers are searching for biochemical or imaging markers that might be used to predict the clinical course of dementia versus normal aging patterns or to monitor treatment progress. A better understanding of factors involved in normal and abnormal brain aging will aid our ability to enhance healthy brain aging, for example with dietary and behavioral practices that could prolong normal brain function.