Beyond Alzheimer’s: The 5 Most Common Types of Dementia

Dementia usually occurs in older age, but it’s different from normal aging. In the U.S., around 15% of adults over 68 are diagnosed with some form of dementia. And as the population ages, the total number of people with dementia is increasing.

Many people are familiar with Alzheimer’s disease and the way it can affect memory. But there are actually many different types of dementia, and the earliest symptoms extend well beyond memory. It helps to know the spectrum of dementia and its symptoms, so you know when you — or someone you care about — should see a provider.

What is dementia?

Dementia is a broad term. It includes a group of conditions that affect the way someone thinks and acts. And it means those changes are serious enough to affect daily functions. 

In dementia, neurons (brain cells) are damaged and don’t work as well. The symptoms of dementia depend on what part of the brain is affected. People with dementia experience problems and changes with: 

• Memory

• Learning

• Solving problems

• Judgment

• Behavior

• Personality

How does Alzheimer’s differ from the other types of dementia?

People often say “Alzheimer’s” when they’re referring to any type of dementia. That’s probably because Alzheimer’s is the most common type of dementia. It makes up 2 out of 3 cases of dementia in people over 65 years old. 

Alzheimer’s comes on slowly and first affects short-term memory. As it progresses, memory worsens. And it affects other areas — like language, attention, and behavior. But there are other types of dementia. And a lot of them can look like Alzheimer’s, or vice versa. 

The 5 most common types of dementia and their symptoms

Five types of dementia make up most cases. There are a lot of overlapping symptoms among the different types. But there are also some characteristics unique to each one. The most common types of dementia are:

1. Alzheimer's disease 

Alzheimer's disease typically affects people over age 65. It occurs when neurons die from deposits of abnormal proteins. The first sign of Alzheimer’s is short-term memory loss. People can often recall events from decades ago, but they can’t remember details from an hour ago. The disease is progressive, and behavior changes are common. In the end stages, people lose their ability to think and function.

2. Vascular dementia

Vascular dementia is the second most common type of dementia. It’s caused by conditions that affect blood flow to the brain, like atherosclerosis or stroke. It may come on suddenly after a stroke, or it can develop gradually if tiny strokes go unnoticed over time. 

The early signs of vascular dementia are varied, depending on what part of the brain is affected. But unlike Alzheimer’s, they extend well beyond memory. People with vascular dementia may have trouble performing tasks, understanding instructions, reading and writing, or communicating with others.

3. Lewy body dementia

Lewy body dementia (LBD) is caused by collections of proteins (called “Lewy bodies”) that deposit in the brain. People who have Parkinson’s disease also have these proteins. But in people with LBD, the brain is affected first. 

People with LBD sometimes see things that aren't there (visual hallucinations). It can also cause episodes of decreased responsiveness, or being "out of it." People with LBD may go on to develop motor symptoms, like a tremor, that look like Parkinson’s disease.

4. Frontotemporal dementia

Frontotemporal dementia (FTD) can start earlier than other types of dementia. It most often starts between the ages of 45 and 65. It affects the front and side parts of the brain, which is how it got its name. People with FTD may have unusual behaviors, dramatic personality changes, or problems speaking.

5. Mixed dementia

Mixed dementia means there’s more than one cause for the dementia. In other words, people can have two different types of dementia at the same time. The most common combination is Alzheimer’s and vascular dementia. 

Other types of dementia and their symptoms

There are other causes of dementia that are much less common. Some examples are: 

• Huntington's disease: This is an inherited disease. It’s usually passed down from fathers to sons. It starts with uncontrollable movements when someone is in their 30s or 40s. It gets worse over time and affects the way someone walks, talks, and swallows.  Eventually, it also leads to dementia symptoms.

• Traumatic brain injury (TBI): This includes injuries from concussions, contusions, and bleeding in the brain. Most of the time, symptoms from a TBI improve over time. But dementia can occur with moderate or severe TBI. 

• Creutzfeldt-Jakob disease (CJD): CJD is a rare but deadly brain disease caused by a prion protein. People experience a rapid progression of dementia, difficulty walking, and uncontrollable muscle movements. Most people die within 1 year of developing symptoms. 

• Parkinson's disease: People with Parkinson's disease usually develop dementia in the later stages of the condition. Their dementia symptoms start well after the motor symptoms — like slow movement, shuffling gait, and tremor.

Conditions that cause dementia-like symptoms

There are many conditions that can cause symptoms that look like dementia. This is why it can take some time to diagnose dementia. Healthcare providers will run tests to look for other causes of someone’s symptoms — many of which are reversible. A few examples include:

• Stroke: Strokes can cause abrupt changes in memory, thinking, and even personality. They can also cause speech problems that may appear like confusion. 

• Infections and autoimmune disorders: Brain inflammation or infections (encephalitis, meningitis) affect how the brain works. And infections in other parts of the body (like urinary tract infections) can also cause dementia-like symptoms.

• Electrolyte changes: Changes in electrolyte levels in the blood, like sodium, can often cause confusion. This can also happen with drops in blood sugar, a common problem in people with diabetes.

• Thyroid disease: Myxedema, a severe form of hypothyroidism, can cause grogginess and confusion. 

• Nutritional deficiencies: There are several vitamin deficiencies that can cause confusion and memory problems — especially if they have been going on for a while. Examples include B12, folate, and thiamine (vitamin B1) deficiency. 

• Medication side effects: Many types of medications can slow down thinking and cause sleepiness or confusion. Examples include opioid pain medications, benzodiazepines, some antidepressants, and antihistamines. This is especially true for older adults, who don’t metabolize medications the same way as younger people. 

• Normal pressure hydrocephalus: This is when there’s too much fluid in the brain. It causes walking and balance problems, urinary incontinence, and dementia-like confusion. 

• Depression: Mental health conditions, like depression, can be mistaken for dementia. 

• Difficulty hearing: It’s common for someone to seem confused or forgetful when the real problem is that they just can’t hear well. 

These are just a few examples of the many conditions that can cause dementia-like symptoms. 

What to do if you think someone has dementia

If you think you or someone you know may have dementia, a trip to a primary care provider is a great place to start. A visit with a regular provider is appropriate if someone’s symptoms: 

• Have been going on for several months

• Are mild

• Don’t threaten their safety

A primary care provider can perform a detailed exam and mental-status testing. They can also order further testing — like a brain scan or blood tests — to rule out other conditions.  

But it’s important to seek immediate medical attention if someone suddenly becomes unresponsive or completely confused. The emergency room is also the best place for life-threatening conditions like a stroke.

Why trust our experts?

Written by:

Shane McCarthy, DO

Shane McCarthy, DO, practices full-spectrum family medicine and is board certified through the American Board of Family Medicine. She has over 20 years of experience.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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