Brain Development: Late Adulthood

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Synopsis

In this activity, you will observe animated illustrations of brain development in late adulthood. To demonstrate the normal aging processes, the animation will show the decrease in brain tissue accompanied by an enlargement of the ventricles as well as a microscopic view of the loss of gray matter and white matter. To show an impaired brain of older adults, you will see views that present changes in the brain of someone with Alzheimer’s disease, multi-infarct dementia, and Parkinson’s disease.

In most cases, late adulthood is a time of continued connection to family, friends, vocations, and leisure activities for many people. Bodies and brains change with age, and some functions typically decline as part of a process known as senescence. However, you will see how these typical brain changes probably have little effect on the everyday behavior of people in good health after the age of 65.

Starting in the early 20s and continuing through late adulthood, there is a gradual loss of brain volume as the gyri (“hills”) of the cerebral cortex become narrower and the sulci (“valleys”) become wider. The loss of brain volume coincides with an increase in the size of the ventricles, the inner chambers of the brain that are filled with cerebrospinal fluid.

As a first sign that the brain is aging, thinning appears in the gray matter layer, where neurons are concentrated. This is usually detectable in the brain of a person’s in his/her early 20s, but this thinning may start even earlier. In contrast to the thinning of the gray matter, the white matter, which includes myelinated axons and support cells, increases until about age 40 after which its volume decreases throughout the rest of a person’s life.

Other brain changes are clearly related to a “brain slowdown” during late adulthood that includes the typical decrease in reaction time and in the speed of information processing. These changes in brain function are related to the reduction in the production of neurotransmitters, in the total volume of neural fluid, in the speed of cerebral blood flow, and in the pace of activation in various parts of the brain.

Interestingly, brain slowdown may not have much effect on thinking in everyday contexts where expertise, rather than not speed, is required. Expertise can compensate for slowdown, and it gives older adults the clear advantage over teens and younger adults in many situations.

A common form of dementia is Alzheimer’s disease, a disorder characterized by a loss of brain tissue that is greater than that which normally occurs in aging. This degeneration causes the gyri to become thinner, the sulci to become wider, and the fluid-filled ventricles to become larger.

Play the animation to compare a brain that has aged normally with the brain of a person who has Alzheimer’s disease.

The most common of these is multi-infarct dementia, a condition in which a blockage or blockages of arteries in various parts of the brain occur. Over time, a person with these types of blockages may acquire multiple areas of brain damage. People with multi-infarct dementia usually show a progression of their condition in marked steps in contrast to those with Alzheimer’s disease whose symptoms are steadily progressive.

Play the animation to observe multi-infarct dementia, a form of vascular dementia.

These neurons communicate with other neurons in the circuit by releasing the chemical neurotransmitterdopamine from their axon terminals. When large numbers of these neurons die, the circuit malfunctions, and the symptoms and signs of Parkinson’s disease, such as stiffness, slowness and tremor, emerge.

Play the animation to observe the brain changes and motor symptoms of Parkinson’s disease.

There are normal changes that occur in every person’s brain during late adulthood. Reaction times and information processing are slower than in early and middle adulthood, but in many everyday settings, this slowdown does not matter that much. Expertise, good judgment, a healthy lifestyle, and strong social bonds allow most adults to enjoy old age.

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