Changes That Occur to the Aging Brain: What Happens When We Get Older

It's no secret that our bodies change as we grow older. Over time, we feel aches and pains in the joints we once used to spring up and out of bed in the morning. But in addition to our bodies changing as they grow older, our brains are constantly transforming throughout our lives—and it’s not as simple as you might think. Some functions like memory, processing speed, and spatial awareness deteriorate as we age, but other skills like verbal abilities and abstract reasoning actually improve.

Why does this happen, though? And what does the changing nature of our most complex organ tell us about our aging selves and our aging population from a public health perspective? 

What Changes Occur When the Brain Ages?

In the early years of life, the brain forms more than a million new neural connections every second. By the age of 6, the size of the brain increases to about 90% of its volume in adulthood.

Then, in our 30s and 40s, the brain starts to shrink, with the shrinkage rate increasing even more by age 60. Like wrinkles and gray hair that start to appear later in life, the brain's appearance starts to change, too. And our brain’s physical morphing means that our cognitive abilities will become altered. The following changes normally occur as we get older:
 

• Brain mass: While brain volume decreases overall with age, the frontal lobe and hippocampus - specific areas of the brain responsible for cognitive functions - shrink more than other areas. 
  The frontal lobes are located directly behind the forehead. They are the largest lobes in the human brain and are considered to be the human behavior and emotional control centers for our personalities.
  The hippocampus is a complex brain structure embedded deep into the temporal lobe. It plays a major role in learning and memory. Studies have shown that the hippocampus is susceptible to a variety of neurological and psychiatric disorders.

• Cortical density: This refers to the thinning of the outer corrugated surface of the brain due to decreasing synaptic connections. Our cerebral cortex, the wrinkled outer layer of the brain that contains neuronal cell bodies, also thins with age. Cortical thinning follows a pattern similar to volume loss and is particularly pronounced in the frontal lobes and parts of the temporal lobe. Lower density leads to fewer connections, which could contribute to slower cognitive processing.

• White matter: White matter consists of myelinated nerve fibers that are bundled into tracts and transmit nerve signals between brain cells. Researchers believe that myelin shrinks with age, slowing down processing and reducing cognitive function. White matter is a vast, intertwining system of neural connections that join all four lobes of the brain (frontal, temporal, parietal, and occipital), and the brain’s emotion center in the limbic system. 

• Neurotransmitter systems: The brain begins to produce different levels of chemicals that affect neurotransmitters and protein production, ultimately leading to a decline in cognitive function.

With these changes, older adults might experience memory challenges like difficulty recalling names or words, decreased attention, or a decreased ability to multitask.

As the brain ages, neurons begin to die, and the cells also produce a compound called amyloid-beta. Amyloid beta is what is typically associated with Alzheimer's. It can also be found in the brain of an individual who is aging. If there are amyloid-beta plaques (prions) in the brain, it can be a sign of Alzheimer's disease. And when there are signs of plaque, but no prions, it may be a sign of normal aging.

Overall, as the brain ages, it does get more difficult for older individuals to care for themselves.

The Connection of Aging and Public Health

With life expectancy almost doubling over the last century and the aging population on the rise, our aging society is a public health issue. Here at the Columbia Mailman School of Public Health, we believe that meeting the needs of our aging society is one of the most significant public health challenges of the 21st century.

We need public health leaders in government, research institutions, and more to help us understand the societal implications of our aging society and establish policies and programs that ensure the well-being of the aging population.

One example of the intersection of aging and public health is the Healthy Brain Initiative. In 2005, the Alzheimer's Association and the Centers for Disease Control and Prevention (CDC) launched this initiative, developed to disseminate the understanding and support of cognitive aging as a central component of public health practice.

If you’re passionate about the intersection of aging and public health, check out our Health of an Aging Society Certificate.