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How Your Brain Changes with Age

Sep 8 2021
9 min read
Close-up of older man's arm wrapped around a toddler.

Like the rest of your body, your brain changes with each passing year.

From the time we are infants, our brains are adapting, learning, making memories and more. We become smarter and sharper, earning the wisdom that truly only comes with life experience. The less desirable effects of the march of time can certainly be felt, too. You may recognize them: An ever-lost set of keys, a to-do that never seems to stay top of mind, a name that’s on the tip of your tongue.

Once we hit our late twenties, the brain’s aging process begins and we begin losing neurons—the cells that make up the brain and nervous system. By our sixties, our brains have literally begun to shrink. Though these brain changes may sound a bit scary, the process is natural and it happens to everyone.

Learn how your brain changes as you age to get a better handle on what is happening in this magical part of your body. Then, review some of the things that you can do to help preserve brain health. Though some change is inevitable, some can be warded off with a healthy lifestyle. Here’s how you can take an active role in slowing negative effects and working to stay sharper, longer.

Birth to Toddler Years

You are born with basic survival skills, reflexes and most of the 100 billion neurons that you’ll have for the duration of your life. The brain grows incredibly rapidly during these early years: Neurons get bigger, work more efficiently and—as a result of environmental input and stimuli—make trillions of connections that fine-tune everything from hearing to vision. By two years old, your brain is about 80 percent of its adult size.

Early to Middle Childhood

About 85 percent of brain development has occurred by now, including intellect, personality and motor and social skills. A child’s brain has twice as many synapses as an adult’s brain. In a process called pruning, the neural connections that are used and reinforced most often—like those used for language—are strengthened, while the ones that are not utilized as much fizzle and die. (That’s why parents are often encouraged to repeat certain activities, like reading books, with their kids every day.)


At this point the brain reaches its adult weight of about three pounds. Increased activity in the frontal lobes allows a teenager to compare several concepts at once.


The regions in the frontal lobe that are responsible for judgment, planning, weighing risks and decision-making finally finish developing. A twenty-something’s brain has reached its peak in terms of performance.

Late 20s to Early 30s

Reasoning, spatial skills and speed of thought begin to decline around now. As you age, your brain goes through changes that can slow down your thinking: It loses volume, the cortex becomes thinner, the myelin sheath surrounding the fibers of your neurons begins to degrade, and your brain receptors don’t fire as quickly.

Mid 30s

What was that woman’s name, again? In your 30s, memory begins to slip as the number of neurons in the brain decreases. It may take longer to learn new things or memorize words or names. This process continues in the decades ahead.

40s and 50s

From your mid 40s to late 50s, your reasoning skills slow. In a group of people who were first tested on various mental abilities when they were 45–49 years old, reasoning skills declined by 3.6 percent over 10 years, according to research in the British Medical Journal. The middle-age participants also experienced fading sharpness in memory and verbal fluency—the ability to say words quickly in a specific category.

On the upside, other measures of cognition—such as moral decision-making, regulating emotions and reading social situations—have been shown to improve beginning with middle age. Experts suspect that simply living life and gaining experience deserves some of the credit. (Bonus fact: Starting at around age 40, people tend to remember positive images more than negative ones—a trend that continues until at least age 80.)


The brain has begun to shrink in size and, after a lifetime of gaining accumulated knowledge, it becomes less efficient at accessing that knowledge and adding to it. The greatest risk factor for Alzheimer’s is advancing age, and most individuals with the disease are 65 or older. Surprisingly, when Alzheimer’s hits people in their 60s and 70s, they show faster rates of brain tissue loss and cognitive decline compared to patients 80 years and older, according to researchers at the University of California, San Diego School of Medicine. Researchers aren’t sure why Alzheimer’s is more aggressive in younger patients, but suspect that people who develop symptoms later in life may have milder cases—or cases that that take longer to reveal themselves.

70s and 80s

Your risk of developing Alzheimer’s increases with age, reaching 50 percent by age 85. Researchers aren’t sure why the risk jumps so dramatically as we get older, but it’s possible the disease is linked to inflammation, a natural part of aging that can lead to a build-up of deposits in areas like the hippocampus, the part of the brain responsible for forming new memories. These deposits may also interfere with long-term memory. Along with aging, many experts think that genes and lifestyle contribute to the majority of Alzheimer’s and dementia cases.

Proven Brain Boosters

Even the healthiest among us cannot stop our brains from changing with time. That being said, certain behaviors can help your brain stay as sharp as possible:

Break a Sweat. Exercise pumps blood to the brain and encourages the growth of new brain cells—and you don’t have to spend hours at the gym to get the positive effects. Research shows that regular aerobic exercise, like walking or cycling, for 30 minutes a day reduces brain cell loss. (Regular physical activity can also significantly reduce the risk of heart attack, stroke, diabetes and more.)

Challenge Yourself. Studies show that mentally stimulating activities may help reverse cognitive decline. Just as lifting dumbbells strengthens your muscles, keeping your mind engaged seems to increase the brain’s vitality and may build its reserves of brain cells and connections. Do stimulating activities that you enjoy: Read, write, put together a jigsaw puzzle, work on crosswords…it all counts.

Listen to Music. A study in the journal Neuron showed that listening to music may sharpen the brain’s ability to anticipate events and stay focused. Researchers took an MRI of people’s brains while they were listening to symphony music, and then when they weren’t. When music played, the areas of the brain involved with paying attention, making predictions and accessing memories were engaged; the same couldn’t be said when it was quiet.

Nurture Your Relationships. Invest in your bonds with friends and loved ones. Experts suspect that social interaction requires you to engage the areas of the brain involved in memory and attention, the same mental processes that are used in many cognitive tasks. Furthermore, one study revealed that activities that combine social interaction with physical and mental activity may help prevent dementia. Sign up for a dance class, which allows you to spend time with pals, get moving and challenge your brain as it works to keep up with all those tricky steps.

Eat Wisely. Certain foods are rich in vitamins and other nutrients that can help thwart threats to your brain health. For example, regularly eating vibrantly-hued fruits and vegetables, which have high levels of disease-fighting antioxidants, will help counteract disease-causing free radicals throughout the body, including the brain. Cook meals with ingredients containing mono- and polyunsaturated fats, which can improve levels of HDL (“good”) cholesterol and—according to research—may help protect brain cells.

Drink in Moderation. While we do not recommend taking up drinking alcoholic beverages, you might be surprised to learn that drinking alcohol sparingly may be beneficial to your brain. At least five studies have linked low-dose alcohol consumption—a drink a day for women, two for men—with a reduced risk of dementia in older adults. Be careful not to go outside those limits: Heavy alcohol use has been linked to an increased risk of dementia and cognitive decline, among other health concerns.

Stay Smoke-Free. Smoking can affect your body’s ability to deliver to the brain oxygen and nutrients that help keep it healthy, and some studies have indicated that it can even speed up the brain’s natural aging process. Smoking can also lead to the formulation of plaques that can contribute to dementia.

Protect Your Head. Experts think that there may be a connection between serious head injury and Alzheimer’s disease, especially when trauma occurs repeatedly or involves loss of consciousness. Protect your brain by wearing a seatbelt, using a helmet when participating in sports and fall-proofing your home.