Types of Dementia

Medically Reviewed By William C. Lloyd III, MD, FACS
Senior African American man looking concerned while senior African American woman comfort hims

We all forget things from time to time, whether it be a doctor’s appointment or where we put our glasses, and we often blame this on getting older. But outright forgetfulness and confusion that affects quality of life are not inevitable signs of aging. Many men and women live well into their 80s and 90s—and sometimes older—with their mental functions fully intact. So, what is the difference between forgetting things because we’re distracted or busy, and something more serious, like dementia?

What Exactly Is Dementia?

Millions of adults in the United States are affected by dementia, the gradual loss of the ability to think, reason or remember. If you say the word dementia, it wouldn’t be unusual for many people to automatically think of Alzheimer’s disease. But dementia itself is not a disease. It is a syndrome that could be caused by any number of medical conditions or diseases, such as Lewy body dementia, frontotemporal lobe dementia, as well as Alzheimer’s disease.

Dementia is also not the same thing as delirium, which is a disturbed state of mind. Delirium is often caused by outside influences, such as drugs, alcohol or infections. Delirium is usually reversible by treating or removing the cause. Dementia is not.

There are several conditions that can cause varying severity of dementia. The most common types are:

  • Alzheimer’s disease

  • Frontotemporal lobe dementia (FTD)

  • Lewy body dementia

  • Vascular dementia

Some neurological diseases, like Parkinson’s disease and Huntington’s disease, can also lead to dementia as the diseases progress.

Alzheimer’s Disease

Almost 6 million adults in the U.S. are diagnosed with this condition and people who have dementia do have Alzheimer’s disease. So it’s not surprising Alzheimer’s is the dementia-related condition with the highest awareness. Contrary to popular perception, Alzheimer’s disease doesn’t just affect the elderly. While most Alzheimer’s patients begin to show symptoms after the age of 65, about 5% are diagnosed before at a younger age. This is called early-onset Alzheimer’s disease and people can develop symptoms as early as their 40s or 50s.

Researchers don’t know what causes Alzheimer’s disease, but people with the condition have amyloid plaques in their brain that look like clumps and tangled fibers, called tau. Along with other complex changes in the brain, the brain cells become unable to transmit messages as they should. Dementia symptoms worsen as the plaque and tau grow and increase.

Progressing Alzheimer’s symptoms include:

  • Forgetting familiar things, such as places and people’s names; asking for the same information repeatedly

  • Difficulty following familiar routines or instructions

  • Getting lost or wandering

  • Losing track of seasons and important events

  • Spatial or visual disturbances, making it difficult to ride a bike or drive a car

  • Losing track in conversations

  • Showing poor judgment, such as spending money irresponsibly

  • Lack of grooming and loss of ability to perform daily household tasks

  • Social withdrawal and personality changes

Frontotemporal Dementia

Unlike Alzheimer’s disease, frontotemporal dementia (FTD) most often affects adults in their 40s, 50s and early 60s. It is the second most common cause of dementia in this age group, behind Alzheimer’s. In older adults, FTD causes about 25% of dementia cases. However, this type of dementia is difficult to diagnose, so it’s hard for experts to determine exactly how many people have it.

There are several subgroups of frontotemporal dementia. The two most common are behavior variant FTD and primary progressive aphasia, which itself has two subgroups.

With frontotemporal dementia, the brain cells in the frontal lobe and the temporal lobes of the brain die off. The frontal lobe controls functions such as emotional expression, language, and judgment. The temporal lobe controls the mental processing needed for speech, comprehension, and verbal memory.

Some symptoms associated with frontotemporal dementia include:

  • Difficulty with language, including the inability to use the correct words or understand what is being said

  • Poor judgment

  • Loss of empathy

  • Socially inappropriate behavior

  • Inability to plan ahead or follow through with plans

  • Abrupt, frequent mood changes

  • Repetitive or compulsive behaviors

Lewy Body Dementia

Lewy body dementia is the second most common cause of dementia overall in the U.S., affecting more than 1 million adults. The condition is named after German neurologist Dr. Friederich Lewy, who in 1912 discovered the abnormal protein deposits now known as “Lewy bodies.”

People with Parkinson’s disease can develop Lewy bodies in their brain as well. This is called Parkinson’s disease dementia. Lewy body dementia is an umbrella term for both dementia with Lewy bodies and Parkinson’s disease dementia, although you may hear Lewy body dementia and dementia with Lewy bodies used interchangeably.

As with Alzheimer’s disease and frontotemporal dementia, doctors don’t know what causes Lewy body disease, but there does seem to be some overlap between this type of dementia and other diseases, such as Alzheimer’s disease.

Many people with Lewy body dementia have plaques and tau in their brain similar to Alzheimer’s, and people with Parkinson’s disease can develop many Lewy body dementia symptoms, which include:

  • Poor judgment and confusion

  • Difficulty interpreting visual information

  • Delusions

  • Visual hallucinations

  • Acting out dreams during REM (rapid eye movement) sleep

  • Rigid muscles and balance problems, similar to Parkinson’s disease

  • Some memory loss

Vascular Dementia

Vascular dementia is dementia caused by brain damage resulting from impaired blood flow to the brain. Stroke is often the cause, but any condition, such as small vessel disease, that restricts blood flow to brain tissue can cause vascular dementia. The brain degenerates due to chronic poor oxygenation.

Because this type of damage can occur anywhere in the brain, the dementia symptoms can vary considerably. People at higher risk for vascular dementia are those with heart disease, diabetes, high blood pressure, and high cholesterol, as well as those who smoke.

Vascular dementia symptoms can include:

  • Memory loss

  • Confusion

  • Difficulty concentrating or staying on task

  • Difficulty organizing thoughts

  • Restlessness or agitation

  • Depression

  • Difficulty controlling urination or inability to urinate

It is possible to have both Alzheimer’s disease and vascular dementia.

There is no cure for dementia when one of these diseases caused it. But if symptoms are caught early enough, treatment may slow down the progress of some types of dementia. Medications and therapies may also help manage some dementia symptoms. Alzheimer’s disease, frontotemporal dementia, and Lewy body dementia can’t be prevented, but lifestyle changes like quitting smoking or managing cholesterol may reduce your risk for vascular dementia.

Dementia caused by trauma, brain hemorrhage, drug reaction, or other toxicities is treatable and can be reversible. This is why any case of dementia deserves a comprehensive medical evaluation.

If you’re a caregiver to someone with dementia, speak with your healthcare team about any help you may need, including therapy for the emotional stress of coping with progressing symptoms.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Oct 20
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