These surprising early symptoms may be linked to Alzheimer's

It might seem like someone with Alzheimer’s disease or another form of dementia wakes up one morning and suddenly struggles to remember important information. But scientists know that what precedes those first memory symptoms is more complex.

As long as a decade before memory impairment appears, tendrils of the disease are already subtly taking hold. During this time, “a lot of people have no obvious cognitive symptoms, but, actually, brain changes are occurring,” says Yuan Zhang, a social-medical scientist who researches the condition at Columbia University. These changes may even precede the amyloid plaques, detected in imaging tests, that are a known hallmark of Alzheimer’s.

With an estimated 6 million Americans currently experiencing some form of dementia and twice that number expected as the population ages, scientists are urgently focusing on these less visible changes.

Some are exploring brain imaging and gut biopsies for other markers that might reveal earlier dementia signals. Others are seeking clues in the blood. Researchers at Washington University in St. Louis recently reported that a protein linked to Alzheimer’s disease can estimate within a few years when some people develop noticeable symptoms. Still, much more research is needed before these tests can predict who might come down with the disease—and precisely when they might start to experience memory loss.

In the meantime, experts are working to link other physical or social signs that may appear years before a faltering memory. None of these definitively indicate that dementia is on the way. (Thyroid, vitamin-deficiency, and other treatable health issues could be behind some of the changes.) But, especially when they occur in combination, these factors could offer important clues that should trigger further evaluations by physicians, perhaps even leading to earlier diagnoses.

Here are five changes scientists have discovered that might surprise you.

Mismanaged finances

People with dementia often forget to pay their bills. Still, it was unexpected when researchers documented in 2020 that missed payments can begin a full six years before a diagnosis.

A newer study has since revealed that the financial shifts are even more expansive and complex. During those same six years, people also give away more money than they can afford, and they become increasingly susceptible to scams.

They’re also more likely to make risky investments. “People who for years have had a well-diversified portfolio … suddenly start thinking it's a great idea to move their entire retirement account into a stock somebody gave them a hot tip about,” says Lauren Nicholas, a geriatrics professor at the University of Colorado who coauthored the study.

Wealth often drops significantly during these pre-diagnosis years, according to the study, which analyzed credit reports and other financial data. This is especially alarming because in the coming years “you’re going to be diagnosed with a very expensive medical condition, and your body is basically preparing you for that by destroying your finances,” Nicholas says.

Ongoing weight loss

Unexpected weight loss can be a symptom of many conditions, including serious ones like cancer. Once doctors rule out those concerns, though, they may brush off the issue. That could be a mistake, Zhang says.

Researchers have long observed a link between low body mass and dementia, but a study Zhang published in 2024 found that what’s important may not be total weight so much as its downward trajectory. Weight loss often begins a decade before a dementia diagnosis in both men and women, her study found, a process that accelerates in the two to four years prior.

Numerous factors may be involved, Zhang speculates, including a possible loss of appetite or reduced energy for cooking. It’s also possible the weight loss itself accelerates the mental processes. Studies have shown, for example, that leptin levels, a hormone involved with hunger, are implicated in cognitive decline.

(The curious link between Alzheimer’s disease and cancer.)

Subtle language changes

Seven years before an Alzheimer’s diagnosis, people can already show subtle changes in the complexity of their speech, according to research published in the journal The Lancet. When computers analyzed data from a large, longitudinal study of some 1,200 participants, they found certain speech changes that could predict with 74 percent accuracy who will get the disease.

One test segment, for example, employed a picture-description task widely used in dementia diagnosis, where people are asked to describe a drawing of a boy falling off a kitchen stool as he reaches for a cookie jar, his sister and mother nearby. Some people who passed the test nonetheless displayed signs that were later linked with a memory disorder, such as writing their answers in short telegraphic sentences that omitted articles like a and the.

Descriptions were also less precise. Rather than using exacting terms like mother and son, they more often employed generics like woman and boy.

Reduction in sense of smell

People can reduce their sense of smell due to the normal process of aging. Medications like Beta blockers, viral infections—most famously COVID-19—and other medical conditions can also inhibit someone’s ability to pick up aromas or fragrances.

So while a decrease in odor detection does not automatically indicate coming cognitive disease, it can do so. For each point lost on a 16-point sniff test, one study’s participants had a 22 percent higher risk of a subsequent Alzheimer’s diagnosis.

Why might this happen? A 2025 analyses of brain images and tissue samples in both mice and people shows that immune cells in the brain may mistakenly decide nerve fibers linking to the processing center for smell are unneeded and attack them, thereby dismantling these crucial connections. It remains unclear why the immune system erroneously targets the cells in these individuals.

Significant mood shifts

Apathy, irritability, impulsiveness, emotional volatility, and even clinical depression or anxiety can be signs of coming cognitive decline. “At the time, we may think the person has developed depression, but over the next couple of years as they have difficulties with memory, the picture of their diagnosis becomes clearer,” says Lea Marin, chief of geriatric psychiatry at Mount Sinai Behavioral Health Center in New York. (Treating the depression itself is still important for improving quality of life, she notes.)

More than half of the cognitively normal people in one study developed at least one mood symptom in the years leading to a memory diagnosis. Studies like this led the authors of a review article a few years ago to concluded that behavioral change is “widespread in the pre-dementia stage and is closely associated with the progression of cognitive impairment.”

The subtle brain changes, including inflammation and emerging plaque tangles, are inevitably involved in the shifting emotions, “but there's also a component of the person noticing that something is not right,” which could agitate them, Marin says. She thinks that, most likely, both the physical and emotional aspects are involved in changing mood.

(What are the signs of dementia—and why is it so hard to diagnose?)

What patients and their families can do

Whether progression can be stopped once someone observes these early signs isn’t yet known. But there may be cognitive benefits from improving overall health—at any time, but especially when someone notices any of these symptoms—Marin says.

Eating a diet of whole foods and limited sugars and incorporating stress management and group social support, among other things, has been shown to slow dementia progression. Exercise strengthens a leaky blood-brain barrier that may improve brain health, a new animal study revealed. And the health conditions that influence heart disease also impact the brain. High blood pressure in midlife, for example, has been associated with increased odds of later dementia.

Discuss any physical, social, or behavioral alterations you notice in yourself or a family member with your physician, since this may trigger further evaluations, Marin says. Doctors don’t routinely screen everyone for cognitive impairment, but they generally test someone noticing changes. Primary care doctors typically perform an abbreviated exam, while neurologists conduct more comprehensive workups.

Early diagnoses are especially helpful because infusion therapies targeting Alzheimer’s brain plaques work best at the start of the disease. (Clinical trials are underway to evaluate whether these treatments might also work before cognitive issues emerge.)

(Why this Alzheimer’s drug is eliciting both optimism and caution.)

On the finance front, Nicholas suggests that adult children ask their parents to grant read-only access to financial accounts to monitor for unexpected outflows. “It’s best if you can do this year’s in advance, when there isn’t the emotional concern that you’re attacking their cognitive abilities,” she says. It’s also valuable for elderly people to simplify assets, such as replacing a complex stock portfolio with an income-paying annuity.

Even if it’s too early to consider medication, “it’s never too early to make decisions for advanced-care medical planning or financial planning” when dementia could be in someone’s future, Marin says.