Is Age-Related Cognitive Decline Inevitable?

We slow down on some thinking skills, but most people will never have dementia

Beth Howard

Reviewed by

Justin B. Miller, Ph.D.

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Published September 27, 2024

The hands of a woman working on a jigsaw puzzle

Photo Collage: AARP (Source: Getty Images)

Jennifer Silver, a dentist in Calgary, Canada, became alarmed after her 62-year-old father started getting forgetful and confused earlier this year. “He had trouble recalling recent conversations and would often ask the same questions repeatedly,” she says. “There were also instances where he forgot where he had parked his car or struggled to remember the way home from places he had visited regularly.”

Fearing the worst, Silver and her family had her father evaluated for cognitive decline. A neurologist discovered the real culprit: clonidine, a blood pressure medication that can trigger dementia-like symptoms in rare cases. After a switch to a different hypertension drug, lisinopril, her father’s mental state quickly improved.

While the symptoms that plagued Silver’s father were particularly dramatic, minor memory lapses — forgetting a person’s name or why you walked into a room — can also lead to worry that you or a loved one is sliding toward dementia. Thankfully most of the time these fears are unfounded. True, the older you get, the greater the risk that some cognitive abilities will decline. In the Alzheimer’s Association's estimate, 1 in 9 Americans 65 and older is living with Alzheimer’s, the most common cause of dementia.

But flip that statistic on its head for an overlooked reality: “Most of us do not develop dementia,” said Robert Klitzman, M.D., professor of psychiatry at Columbia University, Irving Medical Center at a September presentation, Well+Being: Brain Health & Aging, at The Washington Post, supported by AARP. And there are things we can do to improve our odds.

That's news to people worldwide, according to a 2024 survey of more than 40,000 people reported in the World Alzheimer Report 2024 by Alzheimer's Disease International. Eighty percent of the general public think dementia is a normal part of aging. And 65 percent of health care professionals believe the same.

Normal aging vs. cognitive decline

Accumulating evidence suggests that cognitive decline extensive enough to affect daily living is not inevitable. But that doesn’t mean your brain will always work as well as it did in your 20s.

Cognitive function improves through early adulthood, and then, over time, certain aspects of cognition begin to decline, says Thomas M. Holland, M.D., a physician scientist at the Rush Institute for Healthy Aging at Rush University Medical Center in Chicago. Holland studies the impact of lifestyle modifications on aging and is an advisor on the U.S. POINTER study, which stands for U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk in people 60 to 79.

Normal age-related changes in thinking

Recovery may involve several types of therapy:

Declines: thinking speed, attention, multitasking, holding information in mind, word-finding

Remains the same or improves: vocabulary, reading, verbal reasoning

_{Source: University of California San Francisco Memory and Aging Center}

“Certain abilities — processing speed, for example — slow down [around] the age of 20 or so, when processing speed peaks, to age 70 or 80, when processing speed can be down as much as 50 to 70 percent,” says Howard Fillit, M.D., clinical professor of geriatrics, medicine and neuroscience at Mount Sinai School of Medicine in New York City. (On the plus side, vocabulary and decision-making improves with age.)

Not remembering where you put your keys or your glasses is usually no cause for concern, Holland says. “As we get older, [many people] get distracted more easily,” he says.

More worrisome is not being able to perform the activities of daily life, such as bathing yourself, doing the laundry, cooking and cleaning — “things that you were normally able to do but now find challenging, but not because of a physical impairment,” Holland says. For instance, it might be worrying, “if you were able to balance a checkbook and now you’re having trouble doing it, for instance. I get concerned when someone is not remembering how to get home.”

A dimming of your senses — hearing or vision loss, specifically — can accelerate cognitive decline. The distorted or muted input of “data” requires your brain to do more to process it, Holland says. Plus, he adds, “you start self-isolating, and the loss of socialization can lead to an increase in cognitive decline.”

Evaluating cognitive function

There is no single test for cognitive decline. Tests including the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) are commonly used to screen for issues with memory, thinking and problem-solving skills.

“Then we move on to actual cognitive tests and a cognitive battery,” Holland says. The health care provider will also check for causes beyond dementia, such as depression, vitamin deficiencies or medication side effects, such as what Silver’s father experienced. In addition, neuropsychological testing may be used to identify whether changes in a person’s cognition are consistent with normal aging among healthy adults of the same age.

There are tests for genetic risks, particularly a gene mutation called APOE4, that increase risk for Alzheimer’s disease. “If you inherit one copy of the gene, it doubles your risk, compared to somebody who doesn’t carry APOE4,” says Charles Bernick, M.D., staff neurologist with the Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas. Having two copies of it (one from each parent), confers an even higher risk. But having APOE4 doesn’t mean a person will definitely get Alzheimer’s disease, according to the National Institutes of Health. And APOE4 doesn’t appear to have the same effects in non-white populations.

Genetic testing isn’t recommended for people without Alzheimer’s symptoms. Knowing if a person has the genetic risk comes into play when a person with the disease is considering taking one of the new disease-slowing drugs. “If you carry one copy of APOE4, it puts you at a little higher risk of having side effects,” Bernick says, “and if you carry two copies, you have an even higher risk.”

Shoring up your cognitive reserve

Regardless of whether someone feels their cognitive abilities have started to slip, there’s usually an opportunity to maintain their current level of mental functioning, Holland says. “The big idea behind a lot of the interventions, especially those lifestyle factors, is to prevent the onset of cognitive decline to start with,” he says. “And if someone … has, say, mild cognitive impairment, we want to pause it at that point and prevent progression.”

Whether lost cognitive abilities can be regained is an open question, Holland says. “We now know that there is neuroplasticity, which is the capability to create new neural pathways to potentially regain that functionality.”

Preventing dementia

Part of the reason that cognitive decline is not inevitable is the good news that nearly 50 percent of cases of dementia could be prevented or delayed by tackling 14 risk factors. According to a new report in The Lancet, you can optimize your brain function by doing things like getting active, treating depression, improving high blood pressure and high cholesterol, getting control of diabetes, limiting alcohol and quitting smoking — and the earlier that changes are made, the greater the potential for risk reduction.

Multicomponent interventions in particular show significant potential. A landmark study of older adults from Finland found that those assigned to a program that included a combination of tactics — physical exercise, a healthy diet (think: lots of fruits and vegetables, whole grains, olive oil, lean protein), brain stimulation like learning a new language and control of risk factors like high blood pressure and high cholesterol — improved or maintained their cognitive functioning. Those who received health education alone did not.

Other research shows that regular physical activity like brisk walking can plump up brain volume, which shrinks with age, improve the brain’s processing speed and promote the production of a substance called brain-derived neurotrophic factor (BDNF), which is like fertilizer for the brain, Fillit says. In healthy individuals, “preventive lifestyle management types of intervention can actually modify the course of what we currently think of as normal cognitive aging,” he says.

Even in people with higher genetic risk, lifestyle changes can “at least modify the onset of symptoms,” Bernick says. The key to these strategies is to start now. Says Holland, “Intervening as early as possible is ideal.”

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Beth Howard is a North Carolina–based health and lifestyle writer. She has written for dozens of publications, including U.S. News & World Report, The Wall Street Journal, The Washington Post, Prevention, Better Homes & Gardens and Reader’s Digest.

Justin Miller, Ph.D., is a professor of neurology at University of Washington Medicine and a board-certified neuropsychologist with specialization in neurodegenerative diseases, including Alzheimer’s disease and related dementias and movement disorders.