Changes in brain structure and function may continue throughout life. The overall integrity of brain structure and many neural systems is largely preserved in normal aging, whereas in age-related diseases, specific brain cell types and their connections are damaged or lost. In normal brain aging, these changes may be observed:
Senses and emotions
Aging is associated with changes in sensory systems as well as emotion, motivation, and stress resilience.
Structural neuroimaging and anatomical studies of brain have shown declines in total gray and white matter, along with shrinkage or atrophy and synaptic changes in certain regions of the brain in aging.
Brain adaptability and cell metabolism
Functional imaging studies are defining the workings of large-scale neural and cognitive networks in the aging human brain. Human and animal studies suggest that adaptive or resilient processes (i.e., brain plasticity) may be needed for maintenance of brain structure and function during normal aging.
At the molecular and cellular level of analysis in animal models, brain aging is associated with changes in gene and epigenetic expression, mitochondrial and energy metabolism, calcium regulation, protein homeostasis, glia, and neural plasticity and synaptic function.
Risk factors for disease and cognitive decline
In the absence of disease, many of people 85 or above continue to lead healthy and productive lives even into unusually old age. Others, however, suffer from health conditions that can contribute to cognitive decline and dementia, emotional dysfunction, motor instability, and/or sensory deficits.
Systemic risk factors such as obesity, diabetes, hypertension, infection with the human immunodeficiency virus (HIV), and heart disease during midlife are associated with accelerated age-related cognitive decline and with increased risk for Alzheimer's disease (AD), particularly among individuals with three or more of these risk factors. Researchers are examining the mechanisms of how risk factors may influence the transition between normal brain aging and AD, and whether the negative impact of metabolic and vascular risk factors on brain aging can be counteracted through behavioral and lifestyle changes.
Some evidence suggests that diet, physical activity, and other lifestyle factors may promote cognitive health and forestall decline.
Source: National Institute on Aging (NIH), USA.gov