Normal Aging or Dementia? How to Tell the Difference

Everyone forgets things sometimes. You misplace your keys, blank on a word mid-sentence, or walk into a room and can’t remember why. These moments can feel unsettling — especially as you get older.

Occasional forgetfulness is a normal part of brain aging. The brain changes with time, just as the rest of the body does. The more important question is: when do memory problems cross the line from ordinary to concerning?

The difference matters, because early detection of cognitive decline or Alzheimer’s disease can open the door to treatments, planning, and support that make a real difference. Here’s what researchers and clinicians say about how to tell the two apart — and what to do if you’re worried.

What happens to the brain as we age

Aging affects the brain in ways that are visible and measurable. Dr. Andrei Irimia, a quantitative neuroscientist at the University of Southern California, has studied these changes extensively using brain imaging and artificial intelligence.

In the normal aging brain, researchers typically see what’s called atrophy — a gradual shrinking of brain tissue. The ventricles, which are fluid-filled structures inside the brain, tend to enlarge as the surrounding tissue shrinks. These changes are common across most people as they get older.

But there are also patterns of brain aging that look different — and those patterns may signal disease. In Alzheimer’s, researchers see dramatic changes in a region called the temporal lobe and in the hippocampus, a structure deeply involved in forming new memories. 

The rate at which the brain ages also varies from person to person. A healthy diet and regular exercise appear to slow the process. On the other hand, heavy alcohol use, drug abuse, and obesity are all associated with faster rates of brain shrinking, Irimia explained.

Research suggests that diet, physical activity, sleep quality, chronic stress, alcohol and drug use, and social engagement all play a role in how quickly — or slowly — the brain ages over time.

“With a healthy diet and plenty of exercise, the brain ages a bit slower. There are populations out there where, in fact, they’re getting so much exercise that their brains age very slowly,” said Irimai.

Normal forgetfulness vs. warning signs of cognitive decline

Some memory lapses are completely normal. Other kinds of changes go beyond ordinary forgetfulness and may point to something more serious.

Dr. Barak Gaster, cognition in primary care director at the University of Washington, highlights three signs that clinicians should be especially attuned to:

“[There are] three main warning signs for primary care providers,” he said. “These are: losing short-term memory, such as asking the same question repeatedly within a short time; having difficulty completing complex tasks, like following a recipe; and becoming disoriented in familiar places, such as getting lost on a route you’ve taken many times. If these signs are present, they should prompt a cognitive evaluation.”

Beyond these, there are other red flags that experts say should prompt a conversation with a doctor. Frequent confusion about the time or place, difficulty following conversations, repeating the same questions, and noticeable changes in mood, personality, or judgment are all potential warning signs. When loved ones begin expressing concern about changes they’ve noticed, that, too, is an important signal.

What early cognitive decline can look like in everyday life

The early signs of dementia often show up at work or in daily routines — places where the person has always been capable and confident.

LuPita Gutierrez Parker, who was eventually diagnosed with early-onset Alzheimer’s disease, first noticed problems while working as a university recruiter. She started forgetting appointments with counselors, losing track of her notes, and struggling with data entry that had previously been routine. During presentations she’d given many times before, she would lose her place and have difficulty searching for words. A colleague began stepping in to help her pick up where she trailed off. 

Myra Garcia had a similar experience. While working at the University of La Verne, she began having trouble with numbers and remembering colleagues’ names. Technology became increasingly difficult. After moving to a new position as a vice president at a community care organization, she resigned within three weeks because she couldn’t manage the work. Garcia went to multiple doctors before receiving an accurate diagnosis — one physician initially told her she had attention deficit disorder.

Their stories underscore an important point: early cognitive decline can mimic other conditions, and getting the right diagnosis often takes persistence. 

Why Black Americans face a disproportionate risk

By 2030, experts estimate that more than 8 million Americans will be living with Alzheimer’s or another form of dementia. Black Americans are twice as likely as white Americans to develop these diseases — and researchers are still working to fully understand why.

Several interconnected factors appear to contribute. Systemic racism, lower socioeconomic status, food insecurity, and reduced access to healthcare all raise the risk of developing conditions — like hypertension and diabetes — that are themselves linked to cognitive decline. There may also be genetics-related factors that researchers are only beginning to explore.

Renã A.S. Robinson, an associate professor at Vanderbilt University, has pointed to a fundamental barrier in the research itself: studies and clinical trials of Alzheimer’s disease have historically not included enough African American participants. Without that inclusion, Robinson has noted, even explaining why disparities exist — much less reducing them — remains a significant challenge.

How to protect your brain health

While there’s no guaranteed way to prevent dementia, a growing body of research suggests that lifestyle changes can meaningfully reduce risk. Many of the strategies are the same ones that support heart health, metabolic health, and overall well-being.

Regular physical activity may be one of the most powerful tools available. Exercise improves blood flow to the brain and has been associated with slower rates of cognitive decline in multiple studies.

A nutrient-rich diet — particularly the Mediterranean diet, which emphasizes vegetables, fish, olive oil, and omega-3 fatty acids — is also associated with better brain health as people age.

Social engagement appears to matter, too. Research consistently shows that isolation and loneliness are linked to a higher risk of cognitive decline. Staying connected with friends, family, and community may help protect the brain in ways that scientists are still working to quantify.

Challenging the brain with new learning — whether through reading, puzzles, learning a new skill, or engaging with music — may help build what researchers call cognitive reserve, a kind of resilience that helps the brain compensate for age-related changes.

And sleep plays a critical role. During deep sleep, the brain clears out harmful proteins, including beta-amyloid, the substance that builds up in the brains of people with Alzheimer’s disease. Prioritizing quality sleep may be one of the most underappreciated strategies for long-term brain health.

What to do if you’re worried about memory loss

If memory issues are beginning to affect you or a loved one’s daily life, experts say it’s important not to wait.

Keeping a journal of symptoms can help you track patterns and provide useful information for a doctor. Noting when memory lapses happen, how often, and whether they’re getting worse over time gives clinicians concrete data to work with. 

Talking to a doctor about cognitive testing is a reasonable next step, especially if you have a family history of Alzheimer’s or another form of dementia. Neurologist Dr. Marwan Sabbagh has emphasized that the earlier cognitive changes are identified, the more options are available — from emerging treatments to long-term care planning.

It’s also worth knowing that misdiagnosis is common, particularly in younger patients or those from communities where cognitive decline may not be the first thing a doctor considers. If the answers you’re getting don’t feel right, seeking a second opinion and continuing to pursue testing is not only reasonable — it could make all the difference.