6 Medical Problems That Can Mimic Dementia — But Aren’t

Medications, infections and sleep issues can cause you to feel foggy or confused

Michelle Crouch,

Updated December 15, 2025

AARP

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Published March 21, 2022

/ Updated December 15, 2025

A woman looking thoughtfully into her medicine cabinet

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If you’re an older adult experiencing memory lapses, lack of focus or confusion — or you have a loved one with those symptoms — you may be worried about dementia, or its most common cause: Alzheimer’s disease. A recent AARP survey found that half of adults 40 and older think they will develop dementia — a share far greater than the condition’s actual prevalence. Other treatable conditions can cause similar symptoms, and they can be easy for doctors to miss, says Dr. Ardeshir Hashmi, a geriatrician and section chief of Cleveland Clinic’s Center for Geriatric Medicine.

To diagnose Alzheimer’s disease, a neurologist or memory specialist needs to do a thorough evaluation that includes cognitive testing, a neurological exam and sometimes brain imaging or biomarker tests.

Because many treatable conditions can mimic dementia, it’s important to rule out other causes first. “Before you make that conclusion, you should rule out all the other things that can be confused with dementia,” Hashmi says, “things that are easily reversible.”

Here are some common medical problems that can be mistaken for dementia.

1. Medication interactions or side effects

If someone complains of memory problems, Hashmi says his first question is always, “Did you recently start a new medication?”

Older adults are more likely than younger people to develop cognitive impairment as a side effect of a medication, and drug toxicity is the culprit in as many as 12 percent of patients who present with suspected dementia, research shows.

Many types of prescriptions and over-the-counter drugs can affect your cognition, but the most common include those for sleep, urinary incontinence, pain, anxiety and allergies. Taking too many medications (called polypharmacy) can affect your ability to think clearly and remember things, Hashmi says.

An April 2023 report from the National Poll on Healthy Aging found that 82 percent of adults ages 50 to 80 take at least one prescription medication; 28 percent take five or more medications. The same report found that 80 percent of older adults taking prescription medication said they would be willing to stop taking one or more if their doctor said it was possible.

Even a prescription you’ve been on for many years can trigger confusion. The reason, Hashmi explains, is that your kidneys and liver become less effective at clearing drugs from your body as you get older, so a medication can build up in your system and cause problems.

2. A respiratory infection (including COVID-19)

Any untreated infection, Hashmi says, can cause delirium — a sudden change in alertness, attention, memory and orientation that can mimic dementia. When you have an infection, the white blood cells in your body rush to the infection site to fight it off. Those cells release inflammatory chemicals called cytokines into the bloodstream. In older adults, that inflammation can disrupt normal brain signaling, making some older adults feel drowsy, unfocused or confused.

Respiratory infections are harder to diagnose in people 65 and older because they are more likely to lack classic symptoms, such as a fever or a cough, Hashmi notes. In one 2024 study of older adults diagnosed with pneumonia, the majority did not have the typical symptoms; for example, fewer than 1 in 5 had a fever, the study showed.

Delirium tends to come on suddenly, whereas dementia usually progresses slowly, with subtle memory changes that gradually worsen over many years, Hashmi says. “Dementia is almost never sudden onset unless caused by a stroke. If you see a sudden change [in mental status], always think about delirium as a first cause. It is eminently treatable if you get to the trigger or underlying source of it, which is usually an infection.”

Patients have reported difficulty concentrating, memory slips and attention deficits after they recover from a COVID-19 infection. In most patients, those symptoms subside after a few months.

3. A urinary tract infection

Urinary tract infections are another common cause of delirium and dementia-like symptoms in older adults. In surveys, about 1 in 10 women older than 65 and up to 30 percent of women over 85 reported having a urinary tract infection in the past year. Men are also more likely to experience UTIs as they age.

Like respiratory infections, UTIs manifest differently in those older than 65 than in younger patients, says Dr. James M. Ellison, a geriatric psychiatrist who is co-director of the Comprehensive Alzheimer’s Disease Center at Thomas Jefferson University in Philadelphia.

In older adults, “some of the warning signals that help us make a correct diagnosis are altered or absent,” Ellison explains. “So, for example, an older adult with a UTI might experience a mental status change without a fever or burning with urination.”

The good news is that most UTIs, and the accompanying cognitive issues, can be diagnosed with a simple urine test and treated with an antibiotic, Ellison says.

4. Sleep problems

Getting a good night’s rest is essential for protecting the brain as you age, Ellison says. Sleep gives our brain time to learn, store memories and filter out toxic substances. If your sleep-wake cycle is disturbed or you have insomnia, you may experience dementia-like symptoms such as trouble focusing, confusion, mental fatigue and irritability.

Studies have shown that insomnia affects 30 to 48 percent of older people. If you are struggling to get shut-eye, experts recommend limiting or eliminating daytime naps, restricting the use of alcohol and caffeine in the evening and following a consistent sleep schedule and other good sleep hygiene habits. If those remedies don’t work, cognitive behavioral therapy can help. Ellison cautions against the use of sleep medications except in the very short term and under a doctor’s guidance.

Sleep apnea becomes more common with age. Sleep apnea is a breathing problem that can deprive your brain of the oxygen it needs while you slumber, possibly causing long-term damage. Many patients don’t realize they have the condition, Ellison says. Inform your doctor if you have signs of apnea, such as loud snoring, waking up gasping or choking, uncontrolled high blood pressure, a morning headache or a dry mouth upon waking.

If you are diagnosed with sleep apnea, using a continuous positive airway pressure machine (CPAP) while you snooze has been shown to be an effective treatment, Ellison says.

5. Dehydration

Dehydration can look like dementia, and it’s common in older patients, Hashmi says. As you age, your kidney’s ability to retain water in blood vessels decreases, and your blood vessels become stiffer and leakier, so fluid shifts out of your bloodstream more easily. Also, your thirst mechanism isn’t as strong, so it’s easy to get dehydrated without realizing it. Taking diuretics or laxatives can further contribute to water loss.

If someone you love seems foggy or confused, check to see if their urine is dark yellow or brown, which can indicate a lack of fluids. Another sign of severe dehydration is a white coating on the tongue, Hashmi says. Intravenous fluids can often reverse cognitive problems caused by severe dehydration. “It’s amazing what a liter of IV fluid can do,” Hashmi says.

To prevent dehydration, older adults should aim to get at least 48 ounces of caffeine-free fluids (six 8-ounce glasses) each day.

6. Normal pressure hydrocephalus

Normal pressure hydrocephalus is a treatable disorder in which cerebrospinal fluid accumulates in the brain, disrupting and damaging nearby brain tissue and causing cognitive problems.

More than 800,000 Americans have normal pressure hydrocephalus, according to the Hydrocephalus Association, which estimates that less than 20 percent are properly diagnosed. Because symptoms include difficulty walking, forgetfulness and problems with thinking and reasoning, the disorder is often misdiagnosed as dementia, Alzheimer’s or Parkinson’s disease, Ellison says.

A neurologist can diagnose normal pressure hydrocephalus using brain imaging and cerebrospinal fluid tests. It’s commonly treated by inserting a flexible tube, called a shunt, into the brain to drain the fluid.

“We see a couple of cases every year,” Ellison says. “When we diagnose it, we’re always happy because it’s a condition you can treat. ... I’ve seen people improve dramatically.”

Other disorders with dementia-like symptoms

Many other conditions, in addition to the ones above, can cause symptoms that mimic dementia or Alzheimer’s disease, including disorders of the heart, lungs, liver or kidneys, thyroid problems, sodium or vitamin B12 deficiency, some cancers, pain, constipation, heavy alcohol use and depression.

Many of those conditions are treatable, and cognitive symptoms can be reversed, as long as they are properly diagnosed, Ellison and Hashmi say. A routine metabolic blood test and a urinalysis, along with neuroimaging, will pick up many of those disorders.

If tests come back normal, experts suggest asking for a referral to a geriatrician who specializes in older adults, who will do a comprehensive assessment before accepting a diagnosis of Alzheimer’s disease or dementia.

“It’s very important for clinicians and patients to recognize that dementia is not a normal expected part of aging,” Ellison says. About 11 percent of adults 65 and older have Alzheimer’s disease, the most common form of dementia, according to the Alzheimer’s Association. “Everyone deserves a good workup to identify treatable and reversible conditions,” Ellison says.

Editor’s Note: This story, originally published March 21, 2022, has been updated to include new information.

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Michelle Crouch is a contributing writer who has covered health and personal finance for some of the nation’s top consumer publications. Her work has appeared in Reader’s Digest, Real Simple, Prevention, The Washington Post and The New York Times.

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