Sleep disorders in the elderly — more than just insomnia

Reviewed by the How To Help Your Elders Team

Dementia is misdiagnosed more often than most families realize. Research suggests that 10 to 30 percent of people diagnosed with dementia during life had something else when their brains were examined after death. Several common conditions, including thyroid disease, vitamin B12 deficiency, depression, and normal pressure hydrocephalus, mimic dementia and are treatable. If the diagnosis doesn't match what you're seeing, push for a second opinion.

The Short Answer: If Something Doesn't Feel Right, You're Allowed to Ask

Your father came home from the neurologist with a diagnosis of early Alzheimer's disease. The doctor spent maybe fifteen minutes with him. They did some cognitive testing, looked at an MRI, and said the diagnosis was probable Alzheimer's. You're supposed to go home and accept it, start researching memory care. But something doesn't feel right. His forgetfulness is recent. It's not matching the pattern you read about. He's still entirely himself in ways that don't fit the story the doctor told.

So you start researching. You wonder if you should ask for a second opinion. You wonder if you're in denial, refusing to accept the diagnosis because you don't want it to be true. You wonder if you're wasting time pushing back against a specialist when you should just accept it and make plans.

Dementia is diagnosed wrong all the time. Not because doctors are incompetent, but because the human brain is complicated, and dementia mimics are more common than many people realize. There are times when the second look changes everything. And there are times when the diagnosis is wrong and a different treatment might actually help, might actually reverse what's happening.

The Misdiagnosis Problem

Dementia, particularly Alzheimer's disease, is diagnosed by taking a clinical history, doing cognitive testing, and looking at brain imaging. It's not like cancer, where a biopsy confirms the diagnosis under a microscope. The diagnosis of Alzheimer's is actually "probable Alzheimer's." You can't know for sure until the person dies and their brain tissue is examined. So every Alzheimer's diagnosis comes with inherent uncertainty.

The NIH reports that somewhere between 10 and 30 percent of people diagnosed with dementia during life don't actually have dementia when their brains are examined after death. They had something else. Something that might have been treated differently if the diagnosis had been right.

Why does this happen? Partly because dementia symptoms look like lots of other things. Partly because cognitive testing isn't perfectly accurate. Partly because doctors can be rushed and don't have time for a thorough workup. Partly because once one doctor makes a diagnosis, the next doctor might not question it. And partly because if someone comes in with memory loss and confusion, it's easy to think dementia and stop looking.

The Alzheimer's Association emphasizes that a comprehensive dementia evaluation should include a detailed medical history, physical and neurological examination, cognitive testing, blood work to rule out reversible causes, and brain imaging. A diagnosis made in fifteen minutes during a single appointment, without that thoroughness, is less reliable than a diagnosis made carefully over time.

Common Mimics

There are specific conditions that get misdiagnosed as dementia often enough that they have a name: dementia mimics. Knowing about them means you'll know what to ask the doctor about if you're concerned.

Thyroid disease is one of the most common. An underactive thyroid slows down the whole body, including the brain. People with hypothyroidism can be confused, forgetful, slow to think, depressed. They can look like someone with early dementia. But thyroid function is easy to test, and if hypothyroidism is the problem, treating it can improve cognition dramatically, sometimes within weeks.

Vitamin B12 deficiency is similar. Severe B12 deficiency causes neurological problems that can look like dementia: memory trouble, confusion, personality changes, cognitive decline. It's easy to test with a blood draw. Correcting it can actually reverse brain damage, at least if caught early enough. The NIH notes that B12 deficiency becomes more common with age as absorption decreases.

Depression is something doctors sometimes remember to screen for and sometimes don't. Depression in older adults can look a lot like dementia. Your parent might be withdrawn, seem confused, lose interest in things, struggle with memory. The standard name for this presentation is pseudodementia. When depression is treated, the cognitive symptoms often improve. The CDC reports that depression affects approximately 7 percent of adults aged 65 and older, with higher rates among those who are medically ill or institutionalized.

Normal pressure hydrocephalus is rarer but important to know about because it's treatable. Fluid builds up in the ventricles of the brain, causing symptoms that look like dementia. The classic presentation includes trouble walking, urinary incontinence, and cognitive decline. It can be reversed with surgery. But if missed, your parent gets told they have Alzheimer's and never gets the treatment that could help.

There are other conditions too. Lewy body dementia is sometimes misdiagnosed as Alzheimer's, which matters because the treatment is different and some medications that help Alzheimer's can make Lewy body worse. Frontotemporal dementia is sometimes missed because it affects personality and behavior before memory. Chronic subdural hematoma from a fall can cause dementia-like symptoms and can be treated. Medication side effects can cause confusion and cognitive decline that resolves when the medication is stopped.

Even when dementia is the right diagnosis, the type matters. Alzheimer's, vascular dementia, Lewy body, frontotemporal: these are different diseases with different progressions and different treatments. Getting the type right means your parent might get a medication more likely to help, and you'll have more accurate information about what to expect.

When to Suspect It's Wrong

You don't need to be a doctor to wonder if something doesn't add up.

If your parent was diagnosed with dementia and the medication they were given isn't helping at all after months, that's a reasonable reason to question the diagnosis. If the progression doesn't match what you've read about their diagnosed condition, that's worth mentioning. If personality changes are the main thing you're noticing rather than memory loss, that might point to a different type. If depression and apathy are the biggest problems, that might be depression, not dementia.

Something doesn't add up in your gut. You've read about what dementia looks like, and your parent doesn't quite fit. You're not sure if this is denial or intuition, but something's off. That feeling is worth trusting. Your parent is your parent. You probably know them better than the doctor does.

The other reason to question a diagnosis is time. If your parent was diagnosed recently, quickly, after a brief appointment without extensive testing, that's worth questioning. A thorough dementia workup takes time and includes cognitive testing, medical history, physical examination, blood tests, and brain imaging. It includes looking for other explanations.

How to Advocate

Start by writing down what you've observed. What specific changes have you noticed? When did they start? What's the progression? Not "my parent is confused" but "my parent forgot my name twice in a month and then remembered it again" or "my parent seems depressed and slow but their memory seems okay when we talk about the past."

Ask the doctor who made the diagnosis what tests were done. Was thyroid tested? Was B12 tested? Was depression screened for? If these things weren't done, that's a reason to ask for them.

Request a second opinion. You can frame it as wanting another neurologist to review the case and confirm the diagnosis. Most good doctors understand that second opinions are reasonable. AARP advises that getting a second opinion on any significant diagnosis is a standard and responsible part of medical care.

Look for a neurologist who specializes in cognitive disorders or dementia. Not all neurologists have the same expertise. A neurologist who specifically focuses on dementia is more likely to have considered alternative explanations.

Ask for comprehensive evaluation if the first wasn't comprehensive. That means cognitive testing, blood work, brain imaging, medical history, and physical examination. It means detailed questions about symptom progression, family history, medications, and other medical conditions.

Be persistent. Doctors are busy and might not be as thorough as you'd like. Requesting specific tests, asking for explanations if tests weren't done, this isn't being a difficult family member. This is advocating for your parent. The stakes are high.

The Relief of Being Right

Sometimes the second look changes everything. Your parent gets re-evaluated. Different tests are done. A different diagnosis is made. And suddenly there's a treatment that might help, or an explanation that makes sense, or hope where there wasn't before.

Your father might get treated for thyroid disease and his confusion clears. Your mother might get evaluated for depression and become herself again on an antidepressant. Your parent might get B12 injections and improve. Your parent might get diagnosed with normal pressure hydrocephalus and get surgery that helps. These things happen. Not always, not for everyone. But often enough that it's worth looking.

Even if the second diagnosis confirms the first, at least you know. You've done your due diligence. You've made sure there's not something treatable being missed. You can move forward without the nagging feeling that you didn't check hard enough.

And you've learned something about how to advocate for your parent with doctors. This matters now, and it will matter even more as your parent's health gets more complicated and the stakes get higher.

Frequently Asked Questions

How common is dementia misdiagnosis?
More common than most people think. The NIH reports that 10 to 30 percent of people diagnosed with dementia during life had a different condition when examined after death. Misdiagnosis is more likely when the initial evaluation was brief or didn't include comprehensive testing.

What are the most common conditions mistaken for dementia?
Thyroid disease (hypothyroidism), vitamin B12 deficiency, depression (pseudodementia), normal pressure hydrocephalus, medication side effects, chronic subdural hematoma, and sleep disorders are among the most frequently missed alternatives. Many of these are treatable or reversible.

Should I feel guilty about questioning my parent's diagnosis?
No. Questioning a diagnosis is responsible advocacy, not denial. Doctors expect and generally welcome second opinions on serious diagnoses. If something doesn't match what you're observing, you owe it to your parent to ask questions.

What tests should a thorough dementia evaluation include?
At minimum: a detailed medical history, neurological examination, cognitive testing (ideally neuropsychological testing, not just brief screening), blood work including thyroid function and B12 levels, and brain imaging (MRI or CT scan). Some cases warrant additional testing like PET scans or cerebrospinal fluid analysis.

What if the second opinion confirms the original diagnosis?
Then you have confidence that the diagnosis is correct, and you can plan accordingly. You've ruled out treatable alternatives. That peace of mind is valuable, and you've established a relationship with a specialist who may be better equipped to manage your parent's care going forward.

How do I find a specialist for a second opinion?
Ask your parent's primary care doctor for a referral to a neurologist who specializes in cognitive disorders or dementia. Academic medical centers often have memory disorder clinics that handle diagnostically complex cases. The Alzheimer's Association can also help connect you with specialists in your area.