How to Diagnose Dementia: the Practical Basics (2023)

“Doctor, do you diagnose dementia? Because I need someone who can diagnose dementia.”

A man asked me this question recently. He explained that his 86 year-old father, who lived in the Bay Area, had recently been widowed. Since then the father had sold his long-time home rather quickly, and was hardly returning his son’s calls.

The son wanted to know if I could make a housecall. Specifically, he wanted to know if his father has dementia, such as Alzheimer’s disease.

This is a reasonable concern to have, given the circumstances.

However, it’s not very likely that I— or any clinician — will be able to definitely diagnosedementia based a single in-person visit.

But I get this kind of request fairly frequently. So in this post I want to share what I often find myself explaining to families:the basics of clinical dementia diagnosis, what kind of information I’ll need to obtain, and how long the process can take.

Now, note that this post is not about the comprehensiveapproach used in multi-disciplinary memory clinics. Those clinics have extra time and staff, and are designed to provide an extra-detailed evaluation. This is especially useful for unusual cases, such as cognitive problems in people who are relatively young.

Instead, in this post I’ll be describing the pragmatic approach that I use in my clinical practice. It is adapted to real-world constraints, meaning it can be used in a primary care setting. (Although like many aspects of geriatrics, it’s challenging to fit this into a 15 minute visit.)

Does this older person have dementia, such as Alzheimer’s disease? To understand how I go about answering the question, let’s start by reviewing the basics of what it means to have dementia.

5 Key Features of Dementia

A person having dementia means that all five of the following statements are true:

  • A person is having difficulty with one or more types of mental function. Although it’s common for memory to be affected, other parts of thinking function can be impaired.The 2013 DSM-5 manuallists these six types of cognitive function to consider: learning and memory, language, executive function, complex attention, perceptual-motor function, social cognition.
  • The difficulties are a decline from the person’s prior level of ability. These can’t be lifelong problems with reading or math or even social graces. These problems should represent a change, compared tothe person’s usual abilities as an adult.
  • The problems are bad enough to impair daily life function. It’s not enough for a person to have an abnormal result on an office-based cognitivetest. The problems also have to be substantial enough to affect how the person manages usual life, such as work and family responsibilities.
  • The problems are not due to a reversible condition, such as delirium, or another reversible illness. Common conditions that can cause — or worsen — dementia-like symptoms include hypothyroidism, depression, and medication side-effects.
  • The problems aren’t better accounted for by another mental disorder, such as depression or schizophrenia.

Dementia — now technically known as“major neurocognitive disorder” — is a syndrome, or “umbrella” term; it’s not considered a specific disease. Rather, the term dementia refers tothis collection of features, which is caused by some form of underlying damage or deterioration of the brain.

Alzheimer’s disease is the most common underlying cause of dementia. Vascular dementia (damage from strokes, which can be quite small) is also common, as is having two or more underlying causes for dementia. For more on conditions that can cause dementia, see here.

What Doctors Need to Do To Diagnose Dementia

Now that we reviewed the five key features of dementia, let’s talk about how I — or another doctor — might go about checking for these.

Basically, for each feature, the doctor needs to evaluate, and document what she finds.

1. Difficulty with mental functions. To evaluate this, it’s best to combine an office-based cognitive test with documentation of real-world problems, as reported by the patient and by knowledgeable observers (e.g family, friends, assisted-living facility staff, etc.)

For cognitive testing, I generally usethe Mini-Cog, or the MOCA. The MOCA provides more information but it takes more time, and many older adults are either unwilling or unable to go through the whole test.

Completing office-based tests is important because it’s a standardized way to document cognitive abilities. But the results don’t tell the doctor much about what’s going on in the person’s actual life.

So I always ask patients to tell me if they’ve noticed any trouble with memory or thinking. I also try to get information from family members about any of the eight behaviors that are common in Alzheimer’s. Lastly, I make note of whether there seem to be any problems managing activities of daily living (ADLs) and instrumental activities of daily living (IADLs).

2. Decline from previous level of ability. This feature can behardfor me to detect on my own during a single visit.To document a decline in abilities, a doctor can interview other people, and/or document that she’s reviewed previouscognitive assessments. I have also occasionally documented that a patient is currently unable to correctly perform a cognitive task that is related to her career or education history. For instance, if a former accountant can no longer manage basic arithmetic, it’s reasonable to assume this reflects a decline from previous abilities.

3. Impairment of daily life function.This is another feature that can be tricky to detect during a single visit, unless the patient is very impaired. I usually start by finding out what kinds of ADLs and IADLs help the person is getting, and what kinds of problems have been noted. This often meanstalking toat least a few peoplewho know the patient.

Driving and managing finances require a lot of mental coordination, so as dementia develops, these are often the life tasks that people struggle with first.

In some cases — usually very early dementia — it can be quite hard to decide whether a person’s struggleshave become enough to qualify as “impairment of daily life function.” If someone isn’t taking his medication, is that just regular forgetfulness? Ambivalent feelings about the medication? Or actual impairment due to brain changes? If I’m not sure, then I may document that the situation seems to be borderline, when it comes to impairment of daily life function.

4. Checking for reversible causes of cognitive impairment.I mentally divide this step into two parts. First, I consider the possibility of delirium, a very common state of worse-than-usual mental function that’s often brought on by illness.For instance, I’ve noticed thatolder people are often mentally assessed during or after a hospitalization. But that’s not a good time to try to definitely diagnose dementia, because many elders develop delirium when they are sick, and it can take weeks or even months to return to their previous level of mental function.

(My approach to considering dementia in older adults who are confused during or after hospitalization: Make a note that they may have underlying dementia, and plan tofollow-up once the brain has had a chance to recover.)

After considering delirium, I check to see if the patient might have another medical problem that interferes with thinking skills. Common medical disorders that can affect thinking include depression, thyroid problems, electrolyte imbalances, B12 deficiency, and medication side-effects. I also consider the possibility of substance abuse.

Checking for many of these causes of cognitive impairment requires laboratory testing, and sometimes additional evaluation.

If I do suspect delirium or another problem that might cause cognitive impairment, I don’t rule out dementia. That’s because it’s very common to have dementia along with another problem that’s making the thinking worse. But I do plan to reassess the person’s thinking at a later date.

5. Checking for other mental disorders.This step can be a challenge. Depression is the most common mental health problem that makes dementia diagnosis difficult. This is because depression is not uncommon in older adults, and it can cause symptoms similar to those of dementia (such as apathy, and poor attention). We also know that it’s quite common for people to have both dementia and depression at the same time.

In many cases, there may be no easy way to determine whether an older person’s symptoms are depression, early dementia, or both.So sometimes we end up trying a course of depression treatment, and seeing how the symptoms evolveover time.

It’s also important to consider the older person’s mental health history.Paranoia and delusions are quite common in early dementia, but could be related to a mental health condition associated with psychosis, such as schizophrenia.

Is it Dementia or Mild Cognitive Impairment?

Sometimes, when an older person is having memory problems or other cognitive issues, they end up diagnosed with “mild cognitive impairment.”

Mild cognitive impairment (MCI) means that a person’s memory or thinking abilities are worse than expected for their age (this should be confirmed through office-based cognitive testing), but are not bad enough to impair daily life function.

The initial evaluations for MCI and dementia are basically the same: doctors need to do a preliminary office-based cognitive evaluation, ask about ADLs and IADLs, look for potential medical and psychiatric problems that might be affecting brain function, check for medications that affect cognition, and so forth.

I explain more about MCI in this article:.

But remember: in practical terms, if an older person’s memory problems have gotten bad enough that he can’t grocery shop the way he used to, or she can no longer manage her finances on her own…those qualify as impairment in daily life function. And so, a diagnosis of “mild cognitive impairment” is probably not appropriate for those cases.

To learn more about the difference between mild cognitive impairment, Alzheimers and dementia, watch this video:

Can Dementia Be Diagnosed During a Single Visit?

So can dementia be diagnosed during a single visit? As you can see from above, it depends on how much information is easily available at that visit. It also depends on the symptoms and circumstances of the older adult being evaluated.

Memory clinics are more likely to provide a diagnosis during the visit, or shortly afterwards. That’s because they usually request a lot of relevant medical information ahead of time, send the patient for tests if needed, and interview the patient and a family member (or other knowledgeable “informant”) extensively during the visit.

But in the primary care setting, and in my own geriatric consultations, I find that clinicians need morethan one visit to diagnose dementia or probable dementia. That’s because we usually need to order tests, request past medical records for review, and gather more information from the people who know the older person being evaluated. It’s a bit like a detective’s investigation!

Can Dementia be Inappropriately Diagnosed in a Single Visit?

Sadly, yes. Although it’s common for doctors to never diagnose dementia at all in people who have it, I have also come across several instances of busy doctors rattling off a dementia diagnosis, without adequately documenting how they reached this conclusion. (It’s also common for them to hardly document anythingin terms of the older peron’s cognitive state, other than “confused, didn’t know date.”)

Now, often these doctors are right. Dementia becomes common as people age, so if a family complains of memory problems and paranoia in an 89 year old, chances are quite high (at least 60%, according to UpToDate) thatthe older person has dementia.

But sometimes it’s not. Sometimes it’s slowly resolving delirium along with a brain-clouding medication. Sometimes it’s depression.

It is a major thing to diagnose someone with dementia. Soalthough it’s not possible for an average doctor to evaluate as thoroughly as the memory clinic does, it’s important to document consideration of the five essential features of dementia that I listed above.

If You’re Worried About Possible Alzheimer’s or Dementia

Let’s say you’re like the man I spoke to recently, and you’re worried that an older parent might have dementia. (Remember, most dementia is due to Alzheimer’s or a similar underlying brain condition.) You’re planning to have a doctorassess your parent. Here’s how you can help the process along:

  • Obtain copies of your parent’smedical information, so you can bring them to the dementia evaluation visit.The most useful information to bring is laboratory results and any imaging of the brain, such as CAT scans or MRIs. See this post for a longer list of medical information that is very helpful to bring to a new doctor.
  • Write down worrisome behaviors and problems, and bring this documentation to the visit. You can start with this list of 8 behaviors to track if you’re concerned about Alzheimer’s.
  • Consider who else might know how your parent has been doing and behaving recently: other family members? Close friends? Staff at the assisted-living facility? Ask them to share their observations with you and jot down what they tell you. Share these notes, along with the names of the informants, with your parent’s doctor.
  • Be prepared to explain how your parent’s abilities have changed from before.
  • Be prepared to explain how your parent is struggling to manage daily life tasks, such as work, house chores, shopping, driving, or any other ADLs and IADLs.
  • Bring information about any recent hospitalizations or illnesses.
  • Bring information about any history of depression, depressive symptoms, or other mental illness history.

By understanding what it takes to diagnose dementia, and by doing a little advance preparation when possible, you will improve your chances of getting the evaluation you need, in a timely fashion.

Watch this Youtube video to learn six ways getting evaluated for memory loss benefits an older person and their family:

And if you have an aging parent who is refusing to get evaluated for memory loss or other concerning symptoms: my free online training for families (see below) covers how to get past this, and includes a nifty PDF summarizing what to say and not say to your parent who may have dementia.

This article was first published in 2015, and was last updated by Dr. K in April 2022.

Top Articles
Latest Posts
Article information

Author: Nicola Considine CPA

Last Updated: 02/13/2023

Views: 5924

Rating: 4.9 / 5 (49 voted)

Reviews: 80% of readers found this page helpful

Author information

Name: Nicola Considine CPA

Birthday: 1993-02-26

Address: 3809 Clinton Inlet, East Aleisha, UT 46318-2392

Phone: +2681424145499

Job: Government Technician

Hobby: Calligraphy, Lego building, Worldbuilding, Shooting, Bird watching, Shopping, Cooking

Introduction: My name is Nicola Considine CPA, I am a determined, witty, powerful, brainy, open, smiling, proud person who loves writing and wants to share my knowledge and understanding with you.