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Beyond Alzheimer’s: Common Types of Dementia in Aging

Are you dealing with a diagnosis of dementia?

If so, you might be wondering what type of dementia you are dealing with. Or, perhaps you’ve heard someone say it’s important to find out what type of dementia it is.

It’s true that there certainly are different types of dementia, and it’s often said that the most common one is Alzheimer’s disease.

But actually, especially as people get to be age 80 or older, by far the most common type of dementia is mixed dementia. Meaning, the dementia symptoms are caused by a mix of types.

If you are dealing with memory loss or other forms of cognitive decline, it’s a good idea to know the basics about the different types of dementia.

In this article, I’ll cover:

You can also watch my video covering Common Types of Dementia in Aging:

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Dementia (also known as major neurocognitive disorder) is an umbrella term and a clinical syndrome. Having dementia essentially means having developed chronic cognitive impairments that are bad enough to interfere with independence in daily life activities.

To be diagnosed with dementia, these five things must be true:

Dementia usually develops over time, as brain cells become damaged and die, due to one or more underlying causes (such as Alzheimer’s disease, or one of the other types of dementia).

For more on how dementia is diagnosed, see How We Diagnose Dementia: The Practical Basics to Know.

Alzheimer’s disease is the most common underlying cause of dementia.

It is a slowly progressing neurodegenerative condition that causes the brain to develop amyloid plaques and tangles made of tau protein. As the brain changes progress, brain cells initially malfunction and later die.

Cognitive symptoms of Alzheimer’s disease usually emerge after 10-15 years of brain changes, and often involve short-term memory.

Given enough time, people with Alzheimer’s disease in their brains usually first develop mild cognitive impairment, and then eventually dementia.

(Note: Mild cognitive impairment is another syndrome that can have several underlying causes. Learn more here.)

In short: Alzheimer’s can be considered a type — or underlying cause — of dementia.

Most dementia is caused by neurodegenerative disease. Below are the four most common causes of dementia that affect older adults, along with their more typical early symptoms. (Note that for each type of dementia, there can be a lot of variability in the symptoms.)

1. Mixed dementia

Research has shown that the most common types of dementia in older adults is actually mixed dementia, meaning there is more than one disease process affecting brain cells and causing dementia symptoms.

Before I tell you more about mixed dementia, let me cover the other common types of dementia in older adults, as most mixed dementia is a mix of the conditions listed below.

2. Alzheimer’s disease

How it harms the brain: Alzheimer’s is characterized by the development of abnormal amyloid plaques and tau tangles in the brain, and by slow neurodegeneration of brain cells. These brain changes start 10-15 years before symptoms become apparent. Researchers are still trying to figure out just what are the factors that start and accelerate the Alzheimer’s neurodegeneration process.

How common it is: Experts estimate that Alzheimer’s disease is involved in 60-80% of dementia cases.

Typical early symptoms: The most common early symptoms are problems with short-term memory and with executive function. Reduced insight into one’s problems (technically called anosognosia) is also common.

Other early symptoms can include problems with visualspatial processing, language problems, delusions, paranoia, and apathy.

3. Vascular dementia

How it harms the brain: Vascular dementia is usually caused by the accumulation of problems related to the small blood vessels of the brain. These can include small blockages and small bleeds, and tend to leave small scars behind in the brain. (On brain imaging, these problems often cause “white matter hyperintensities.” Learn more about this type of damage here: Cerebral Small Vessel Disease: What to Know & What to Do.)

How common it is: Experts estimate that cerebrovascular disease is a contributor to 50% of dementia cases.

Typical early symptoms: The most common early symptoms are impaired executive function and slower processing speed. Many people with vascular dementia also have problems with short-term memory.

Researchers believe that some forms of apathy and late-life depression may be related to small vessel vascular damage as well.

4. Lewy body disease

How it harms the brain: Neurons in the brain accumulate abnormal aggregations of alpha-synuclein protein. These are called Lewy bodies. When they accumulate in a certain part of the midbrain that regulates movement, this causes Parkinson’s disease, but in Lewy body dementia, the Lewy bodies have accumulated in other parts of the brain.

How common it is: Experts estimate that Lewy body dementia is involved in 20% of dementia cases.

Typical early symptoms: To be diagnosed with probable Lewy body dementia, a person must have at least two of the following “core clinical features” of dementia with Lewy bodies:

Note: Dementia with Lewy bodies is related to Parkinson’s disease dementia. In Parkinson’s disease dementia, the dementia comes on after the person has had the motor symptoms of Parkinson’s for at least one year. Whereas in Lewy body dementia, the cognitive problems start before or at the same time as the parkinsonism motor symptoms.

Also: Frontotemporal degeneration (FTD)

Frontotemporal dementia is actually not all that common in older adults, but I’m including a little information here, as people ask me about it often. FTD is a more common cause of dementia in people younger than age 65.

How it harms the brain: Neurons degenerate in the front and/or sides of the brain. (The reasons for this are varied, and depend on the subtype of FTD.)

Degeneration in the front of the brain affects behavior in particular, and is associated with behavioral variant FTD. Degeneration in the sides of the brain (the temporal areas) is associated with a variant called primary progressive aphasia, which involves language problems.

How common it is: FTD is a more common cause of early-onset dementia (i.e. occuring before age 65); it’s been estimated to account for 10% of early-onset dementia cases. FTD becomes less common as people get older and is estimated to account for about 3% of dementia cases in people over age 65. Most people diagnosed with FTD are less than 65 years old.

Typical early symptoms: Early symptoms depend on the variant of FTD:

There are many other conditions that can cause dementia. In older adults, conditions I might consider include:

There are also some newer types of dementia pathology that are relevant to older adults. (Dementia pathology means brain changes that are associated with clinical dementia symptoms.) These include:

For those who want to really dig into the science of different dementia pathologies, here is a resource: Neuropathology of Dementia Disorders.

There are some other less common causes of dementia that you might hear about, most of which are likely to affect people younger than 80. They include:

Unfortunately, other than HIV-associated dementia, these rare causes of dementia cannot be cured or slowed down. For these conditions, medical care focuses on managing symptoms and quality of life.

Given all the different things that can cause dementia, you might think that in geriatrics, we’d be spending a lot of time trying to sort out what type of dementia our patients have.

But we usually don’t. That’s because there is one type of dementia that is by far the most common in older adults, and that is mixed dementia.

For instance, an autopsy analysis of 2695 participants found that 91% of them had more than one of six key neuropathologies, and 41% had three or more. Studies of older adults who died at age 80 or older with clinical dementia have shown that it’s uncommon for them to have only a single type of dementia pathology in their brains.

(Interestingly, research done by the Religious Orders Study and Rush Memory and Aging Project found that Alzheimer’s pathology was also present in one third of decedents who didn’t not have outward signs of mild cognitive impairment or dementia. In other words, neuropathology is NOT destiny.)

The most common mix is Alzheimer’s disease and cerebral vascular disease.

The Alzheimer’s Association has a good overview of mixed dementia here: Mixed Dementia.

It depends who you ask.

Personally, I find that most of the time it doesn’t matter all that much, especially once a person is aged 80 or older. In usual clinical practice, what is most important is to identify people who seem likely to have a component of Lewy-body dementia, as they can be very sensitive to antipsychotics (and other drugs) that block dopamine.

Now, I have heard various “experts” recommend getting the type of dementia identified, “so that you can get the right type of treatment” or an “appropriate, specific treatment.”

I find myself wondering in response to this: what “specific” treatment??

Surely these experts must know that we essentially have no treatment that works reliably for the most common types of dementia (with the possible exception of anti-amyloid antibodies such as lecanumab, which have been studied mostly in younger Alzheimer’s patients with mild cognitive impairment or early dementia). So it is not clear to me why it’s valuable to try to identify the type of dementia, unless one is participating in a research study.

Furthermore, once people are in their 80s, they are very likely to have mixed dementia.

That said, if you are dealing with dementia, chances are that someone will recommend further evaluation to get the type diagnosed. Now, it’s true that with more specialized brain imaging and detailed neuropsychological testing, it is often possible for experienced clinicians to identify the likely type of dementia.

But since it doesn’t really change management, it seems to me that it’s usually not a good use of time and effort, if you are dealing with dementia, especially in those aged 80+.

So from a practical perspective, when considering dementia treatment, my main priority is usually to check and consider whether the person has any symptoms of Lewy body dementia. This is important to know because those people can be very sensitive to drugs that block dopamine, and many antipsychotics and other drugs do this.

Otherwise, I feel it’s best to focus on what types of difficulties and symptoms the person is having, and try to find ways to manage those. So for instance, if the main problem is related to memory, then we need to find ways to work around that. If a key problem is processing or expressing language, then we need to see what we can do to improve communication.

The truth is that the best care for Alzheimer’s, mixed dementia, or other types of dementia does not really depend on the underlying type of dementia.

Instead, the best treatment comes from doing things like:

(Note: if you are concerned about an aging parent with dementia, learn more about my Helping Older Parents with Memory Loss program here.)

Medications do sometimes have a role in managing dementia. But the medications FDA-approved for dementia usually have only a small effect. And the medications used for sundowning and difficult behaviors tend to be problematic.

And again, aside from lecanumab (Leqembi), most medications for dementia are not really specific for a type of dementia.

In short, here’s what’s most important to know about Alzheimer’s and other types of dementia in older adults:

I do know it’s very hard to be dealing with Alzheimer’s and other forms of dementia. I do think it’s good to be informed about the most common types, and hope this article has helped you with this.


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