Careblazer, one of the questions I get asked the most is what the most common types of dementia are.
And if your loved one doesn’t have a specific type of dementia in their diagnosis yet, that’s really common. But knowing the most common types can help you understand the differences between them, and even what certain types might look like as the disease progresses and things become clearer down the road.
1. Alzheimer’s Disease: The Most Common Type of Dementia
When someone mentions dementia, most people instantly think of Alzheimer’s disease. A lot of people think they’re the same thing, even though they’re not. I explain the difference in is dementia the same as Alzheimer’s disease?
There’s a good reason the two go together. Alzheimer’s disease is the most common type of dementia.
Estimates say somewhere between 45 and 80 percent of all dementia cases are Alzheimer’s disease. A large study of Medicare claims put it near the low end, and the Alzheimer’s Association puts it at 60 to 80 percent.
A quick reminder of its main characteristics:
- It impacts memory first.
- As it gets worse, it starts to affect other areas of the brain, like language and problem solving.
- The risk increases with age. The older you are, the higher your risk.
- It can absolutely start at a younger age, but it typically starts after 65.
- It’s more common in women.
2. Vascular Dementia: Problems With Blood Flow to the Brain
The second most common type of dementia is thought to be vascular dementia, at about 14.5 percent of dementia cases in that same study.
Vascular dementia really comes down to problems with blood flow to the brain. That’s why conditions that affect blood flow in the body, like blood clots, peripheral artery disease and hypertension, put someone at higher risk. High cholesterol, high blood pressure, heart disease and smoking all raise the risk too.
So managing cardiovascular health is really important.
This type is more common in men. That’s thought to be because men more often have some of those blood flow conditions.
3. Lewy Body Dementia: Good Days and Bad Days
The next most common type is Lewy body dementia. It’s thought to account for about 5.4 percent of dementia cases. But I’ve also seen studies suggesting it’s so confusing and hard to identify that it might be more common than we realize.
It’s caused by protein deposits in the brain called Lewy bodies.
Some of the hallmark symptoms are sleep disturbances and visual hallucinations. Those can show up in every type of dementia, but they’re classic for this one.
People with Lewy body dementia tend to have good days and bad days. Their symptoms wax and wane, so you might notice higher levels of alertness at some points and lower levels at others.
This one is also more common in men.
4. Frontotemporal Dementia: More Common in Younger People
Frontotemporal dementia tends to be more common in younger people.
In that Medicare study, which only counted people 68 and older, it made up about 1 percent of dementia cases. Because it usually starts younger, that number misses a lot of it. A systematic review of frontotemporal dementia studies found it averaged about 3 percent of dementia in studies of people 65 and older, and about 10 percent in studies of people under 65.
It can be hard to catch for two reasons.
First, it typically affects people under 65, and we’re not generally thinking about dementia in younger people.
Second, the first symptoms tend to be changes in personality or behavior, or problems with language. We don’t really see memory problems right away.
I cover the early signs in more detail in frontotemporal dementia signs and symptoms.
5. Mixed Dementia: More Than One Type at Once
This last one is the hard part. Did you know you can have more than one type of dementia?
It’s called mixed dementia, or dementia due to multiple etiologies. It’s most common in older adults. Symptoms vary depending on which areas of the brain are affected, and treatment focuses on the individual symptoms.
The most common combination is Alzheimer’s disease with vascular dementia. That makes sense, because those are the top two types. One study found that combination accounted for about 6.3 percent of dementia cases. Alzheimer’s disease combined with Lewy body dementia made up about 2 percent.
If you suspect your loved one has more than one type, I walk through why it so often gets missed in mixed dementia: the hidden diagnosis doctors often miss.
Why Two People With the Same Type of Dementia Can Look Different
Every person with dementia is unique. Even two people with the exact same diagnosis don’t always have the same symptoms.
The symptoms, the progression and the rate of decline vary from person to person, because other factors are involved. Things like lifestyle, caregiving support, sleep and food all make a big difference in how the disease progresses and how it shows up.
What If You Don’t Know What Type of Dementia Your Loved One Has?
A lot of Careblazers prefer knowing what type of dementia their loved one has, because it gives them more of an understanding of what to expect.
But the majority of people simply don’t have the specific type. They just don’t know.
With time, clearer answers might come. As more symptoms show up and the rate of decline becomes clearer, we get more information. Sometimes that gives us a better understanding of what type it might be. Other times we just don’t know. When that happens, instead of multiple etiologies, it’s called unknown etiology.
Not knowing what to expect is one of the hardest parts of this. Inside the Care Collective, I break down the types of dementia, the symptoms each one tends to have, and the providers involved in dementia assessment and treatment, so you understand what you’re looking at. You can learn more here.
Sources & References
Goodman RA et al. Prevalence of dementia subtypes in United States Medicare fee-for-service beneficiaries, 2011-2013. Alzheimer’s & Dementia, 2017: https://pmc.ncbi.nlm.nih.gov/articles/PMC5104686/
Alzheimer’s Association, What Is Alzheimer’s Disease?: https://www.alz.org/alzheimers-dementia/what-is-alzheimers
Hogan DB et al. The Prevalence and Incidence of Frontotemporal Dementia: a Systematic Review. Canadian Journal of Neurological Sciences, 2016: https://pubmed.ncbi.nlm.nih.gov/27307130/
