Overview of the Types of Dementia & Accurately Making Diagnoses

Last Updated: June 03, 2021


Alzheimer’s disease is by far the most common type of dementia, but there are a number of other related dementias. Each type of dementia has a different cause, and affects people in varying ways. However, they are also similar in so many ways that it can be difficult to tell which type of dementia a person has.

Below are the most common types of dementia, listed in order of how frequently they are seen. All are progressive dementias, meaning they get worse over time, and tend to be seen most often in older age groups. Please note that it is possible for a person to have “mixed dementia,” meaning more than one type of dementia at the same time. In fact, mixed dementia might be more common than Alzheimer’s disease by itself, according to studies.

 Watch a short video that discusses the types of dementia and the importance of diagnosis (1 minute 45 seconds long)


Most Common Types of Dementia

Alzheimer’s Disease (AD) – AD is by far the most common type of dementia, affecting approximately 6 million Americans and around 50 million people worldwide. About 10% of people over 65 have AD, and about 50% of people over 85. The World Health Organization estimates that AD amounts to between 60% and 70% of all dementia cases.

AD affects memory first and later progresses to affect other cognitive (brain) abilities, such as speech, the ability to reason, and movement, until it ultimately becomes impossible for someone with the disease to live independently. Risk factors include age, family history, diet, and head trauma. The average life expectancy for someone with AD is about eight years after diagnosis.

Vascular or Multi-Infarct Dementia – This type of dementia comes from problems with the brain receiving oxygen and blood flow. It is often the result of a stroke (sometimes several small strokes) in which small areas of the brain are irreversibly damaged. The onset of vascular dementia is often sudden. Symptoms can vary more than other types of dementia because vascular dementia occurs in different parts of the brain. Memory might be impaired, but it’s also possible for memory to remain intact while the person’s personality and ability to solve problems will change dramatically.

Vascular dementia is the second-most-common kind of dementia, accounting for between 5% and 10% of cases. Risk factors include high blood pressure, high cholesterol, and diabetes. The average life expectancy for someone with vascular dementia is about 5 years after diagnosis.

Dementia with Lewy Bodies (DLB) – DLB symptoms often include hallucinations, delusions, and movement problems like those experienced by people with Parkinson’s disease. Memory loss also occurs, but a person’s thinking ability will fluctuate from moment-to-moment more often in cases of DLB than with the more common types of dementia listed above. It also strikes at a younger age, usually about 50. A buildup of proteins called Lewy bodies, killing cells and impairing their ability to communicate via nerve signals, is the cause.

DLB is the third-most-common dementia. Its causes are unknown, though environmental and genetic risk factors are believed to play a role. Someone with DLB typically has a life expectancy of between 5 and 8 years following diagnosis.

Frontotemporal Dementia – Abbreviated as FTD, this type of dementia attacks the frontal and temporal lobes of the brain, and differs from others in that it affects personality and speech but not memory. A person with FTD will, for example, demonstrate erratic behavior and bad judgement, and can be prone to acting inappropriately in public. About half of people with FTD have inherited a particular gene (MAPT) that mutates to cause the disease, and genetic testing can determine if someone is high-risk. FTD typically strikes at a younger age than most other dementias, usually between the ages of 45 and 65.

Frontotemporal dementia affects between 50,000 and 60,000 Americans. It used to be called “Pick’s disease,” after the doctor who discovered the protein mutations that cause brain cell death. The average lifespan after a diagnosis of FTD is 6 to 8 years.

 Did You Know? About 5% of cases of Alzheimer’s are young-onset Alzheimer’s disease (YOAD), also called “early-onset” AD. Affecting mostly people in their 30s, 40s, and 50s, the symptoms and process of diagnosing YOAD are similar, but the emotional toll can be worse because the person is in what’s considered the prime years of life.


Rare Forms of Dementia

The following forms of dementia are less common than the previously mentioned dementias and vary as to the cause and age of onset. They often affect different parts of the brain than the diseases listed above, and symptoms vary. About 1 out of every 20 people with dementia live with one of these rarer types:

Parkinson’s Disease Dementia
Huntington’s Disease
● Creutzfeldt-Jakob Disease and Other Prion Diseases
● Dementia in HIV/AIDS
Normal Pressure Hydrocephalus (NPH)
Traumatic Brain Injury
● Wernicke-Korsakoff Syndrome (Includes dementia from alcohol abuse)

To learn more about these lesser-known dementias, click here.


An Accurate Diagnosis is Key

Before addressing problems with dementia, an accurate diagnosis must be made. Sometimes memory problems are not dementia, and they could be temporary or reversible. Delirium is one condition seen in the elderly which can be caused by illness or changes in medication. It is important, therefore, to go through the process of having your loved one assessed by a medical doctor to know if issues with thinking, movement, or both can be cured, or if they must be treated to increase quality of life.

Regardless of what type of dementia your loved one has, whether Alzheimer’s disease or something much rarer, the beginning of the process is the same. If you believe someone is showing signs of dementia, like memory loss or difficulty concentrating, there are easy tests that can be administered at home, like the clock drawing test, to help you know if further steps should be taken or if the problems might be caused by stress, lack of sleep, or some other issue.

The more substantive step toward getting diagnosed is an appointment with a primary care doctor. For this appointment, it’s good to know your loved one’s recent medical history with as much specificity as possible. Make notes on any health, personality, or behavioral changes. It’s also important to know how well your loved one is at performing activities of daily living (ADLs) like eating and getting dressed. Difficulty with ADLs is a major warning sign for dementia.

If your primary care doctor believes dementia might be present, then an appointment will next be made with a specialist, probably either a psychiatrist who is an expert in mental health or a neurologist who specializes in the brain. It may even take a team of specialists working together to determine next steps.

Brain scans are usually part of getting a diagnosis. These include PET and MRI scans that can show whether regions of the brain are changing, and where mental activity is stronger or weaker. A spinal tap might also be necessary.

Combining information including a patient’s history, symptoms, and the results of any tests and scans is how medical professionals are able to diagnose the specific type of dementia. Even after scans, however, it is usually not possible to give a 100% definitive diagnosis of Alzheimer’s or related diseases because confirmation of most dementias is only possible during an autopsy following death. Medical professionals can, however, know with relative certainty whether someone has Alzheimer’s disease or one of the other dementias listed on this page.


Providing Care for a Loved One with Any Type of Dementia

While there are many varying types of dementia, the strategies and tips for caregivers of people who have dementia are similar. If you are providing care at home, you’ll need to learn how to communicate, handle various behavior issues, and what to expect as your loved one moves through stages of the disease. This can be a difficult time for everyone involved, but by actively learning how to handle problems as they arise, and by planning for the future, dementia symptoms can be managed. It is even possible to slow the progress of the disease.

Keep in mind that because dementia are progressive illnesses, your loved one will eventually lose independence, and caregiving will probably need to be taken over by professionals in a community setting like assisted living with memory care. It is best to start the search for a memory care home before the move is necessary. For help finding memory care to meet your needs, click here.