How Aging Affects Memory

Why do we experience changes in our mental abilities as we age? What happens in our brains to cause these changes? And what can we do to keep our minds sharp?

Until recently, scientists could only offer educated guesses about the answer to these questions. Now, however, thanks to sophisticated new brain-imaging technology, they can start to put the pieces of the puzzle together.
In this section we'll learn how aging changes our brains, how aging affects memory, and what you can do to keep your memory sharp.

Some of the most important information scientists have learned about our brains appears below. These concepts—based on animal experiments and human brain-imaging studies—represent what we know today about the effects of aging on our brains.

Understanding how and why brain functions change as we grow older may lead to new therapies and medications that could slow, stop, or prevent these processes altogether.

Of course, other health problems—like high blood pressure, diabetes, or deafness—that people either have or develop as they grow older profoundly affect how their brains change with time.
Specific changes vary greatly from one person to the next, and may include the following, depending on their medical and psychological history:

• Brain mass shrinks
• Outer surface thins
• White matter decreases
• Chemical messengers decrease

Brain mass shrinks: Beginning in our 60s or 70s, some people's overall brain mass may shrink a bit. Certain brain areas shrink more than others, including the frontal lobe (important for mental abilities) and the hippocampus (where new memories are formed).

Outer surface thins: The cortex—the heavily ridged outer surface of the brain—thins slightly with age. This thinning is not, as scientists once believed, the result of widespread loss of brain cells. Instead, the thinning of the brain's outer surface is likely due to a decrease in synaptic connections (a process that starts when we're about 20 years old). Synapses are like intersections. They allow brain cells to communicate with one another and to form connections.

White matter decreases: Many studies have linked aging with decreases in the brain's white matter (so called because it's made up, in part, of myelin—a fatty, white substance). Myelin helps to improve communication between brain cells.

Research shows that changes in white matter are linked with changes in speed of cognitive processing. Cognitive processing includes memory, attention, action, problem solving, and decision-making abilities.

It's important to remember, though, that aging is not a process of decline. Many of our gifts and abilities—including wisdom and problem solving—improve as we age.

Chemical messengers decrease: As our brains age, they generate fewer neurotransmitters (chemicals like serotonin, which carry messages between brain cells), and have fewer receptors that lock onto these messengers. This change may have an effect on memory.