The Aging Brain
National Institute on Aging
The brain controls many aspects of thinking—remembering, planning and organizing, making decisions, and much more. These cognitive abilities affect how well we do everyday tasks and whether we can live independently.
Some changes in thinking are common as people get older. For example, older adults may have:
- increased difficulty finding words and recalling names
- more problems with multi-tasking
- mild decreases in the ability to pay attention
Aging may also bring positive cognitive changes. People often have more knowledge and insight from a lifetime of experiences. Research shows that older adults can still:
- learn new things
- create new memories
- improve vocabulary and language skills
The Older, Healthy Brain
As a person gets older, changes occur in all parts of the body, including the brain:
- Certain parts of the brain shrink, especially those important to learning and other complex mental activities.
- In certain brain regions, communication between neurons (nerve cells) can be reduced.
- Blood flow in the brain may also decrease.
- Inflammation, which occurs when the body responds to an injury or disease, may increase.
These changes in the brain can affect mental function, even in healthy older people. For example, some older adults find that they don’t do as well as younger people on complex memory or learning tests. Given enough time, though, they can do as well. There is growing evidence that the brain remains “plastic”—able to adapt to new challenges and tasks—as people age.
It is not clear why some people think well as they get older while others do not. One possible reason is “cognitive reserve,” the brain’s ability to work well even when some part of it is disrupted. People with more education seem to have more cognitive reserve than others.
The brain is complex and has many specialized parts. For example, the two halves of the brain, called cerebral hemispheres, are responsible for intelligence.
The cerebral hemispheres have an outer layer called the cerebral cortex. This region, the brain’s “gray matter,” is where the brain processes sensory information, such as what we see and hear. The cerebral cortex also controls movement and regulates functions such as thinking, learning, and remembering.
For more information about parts of the brain, see “Know Your Brain” from the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.
How Brain Cells Work
The healthy human brain contains many different types of cells. Neurons are nerve cells that process and send information throughout the brain, and from the brain to the muscles and organs of the body.
The ability of neurons to function and survive depends on three important processes:
- Communication. When a neuron receives signals from other neurons, it generates an electrical charge. This charge travels to the synapse, a tiny gap where chemicals called neurotransmitters are released and move across to another neuron.
- Metabolism. This process involves all chemical reactions that take place in a cell to support its survival and function. These reactions require oxygen and glucose, which are carried in blood flowing through the brain.
- Repair, remodeling, and regeneration. Neurons live a long time—more than 100 years in humans. As a result, they must constantly maintain and repair themselves. In addition, some brain regions continue to make new neurons.
Other types of brain cells, called glial cells, play critical roles in supporting neurons. In addition, the brain has an enormous network of blood vessels. Although the brain is only 2 percent of the body’s weight, it receives 20 percent of the body’s blood supply.