What Is Lewy Body Dementia?

This disease can be hard to distinguish from Alzheimer’s disease, but certain symptoms are different

Marah Stets,

AARP

Reviewed by

Jennifer G. Goldman, M.D.

Comments

En español

Published February 07, 2025

Photo Collage: AARP; (Source: Getty Images (3))

There’s a type of dementia that is named for the specific clumps of protein that aggregate in the brain and cause the damage that leads to changes in cognition, behavior, mood and movement. It’s called Lewy body dementia, and it is actually an umbrella term for two related conditions: dementia with Lewy bodies and Parkinson’s disease dementia. Both conditions involve abnormal buildup of a protein called α-synuclein, which is important for communication between neurons.

When α-synuclein forms clumps, called Lewy bodies, neurons are damaged in areas of the brain that affect thinking, behavior, movement and sleep. Patients often have hallucinations or delusions and can experience rapid eye movement (REM) sleep behavior disorder, which involves a loss of the muscle paralysis that normally occurs during REM sleep. Without the paralysis, a person can move about while dreaming, which can lead to some unsettling situations.

About 1.4 million people in the United States have Lewy body dementia, according to the Lewy Body Dementia Association. It is the second most common cause of neurodegenerative dementia after Alzheimer’s disease, though it is believed to be vastly underdiagnosed. Most cases occur in people age 50 or older. And it is slightly more common among men than women. The disease is progressive, meaning it worsens over time. There is no cure or way to slow it down, but treatments are available to help with some of its symptoms.

Signs and symptoms of Lewy body dementia

The organizations below can help patients and caregivers learn more and find resources.

Lewy Body Dementia Association

https://www.lbda.org/
Helpline: 800-539-9767

National Institute on Aging

https://www.nia.nih.gov/health/lewy-body-dementia

Lewy Body Dementia Resource Center

https://lewybodyresourcecenter.org/
Helpline: 516-218-2026 or 833-LBD-LINE

The Alzheimer’s Association

https://www.alz.org/

Michael J. Fox Foundation

https://www.michaeljfox.org/

Parkinson’s Foundation

https://www.parkinson.org/

Doctors look for four symptoms of Lewy body dementia, though not all four have to be present:

Fluctuating cognition or alertness
Visual hallucinations, that is, seeing things that aren’t there
Sleep disorders, such as acting out or vocalizing while dreaming
Parkinson’s-like movement difficulties, such as stiffness, slowness, tremors, or shuffling walk and falls

Lewy body dementia can be hard to distinguish from Alzheimer’s disease. However, Alzheimer’s primarily affects memory, especially early on, in contrast with Lewy body’s broader range of cognitive symptoms. Lewy body dementia primarily affects executive function (planning, organizing, multitasking), attention, the ability to judge distance and depth, and navigating. Problem-solving and reasoning also become difficult. People with Lewy body dementia show some memory impairment, particularly for “working memory” that we all use to keep track of a topic during conversation or during a multistep project such as preparing a meal. However, they generally have less trouble with recall of recent events or discussions than those who have Alzheimer’s disease.

In addition, there can be behavioral and mood symptoms such as depression, anxiety and apathy. Some people will also have delusions, or false beliefs not based on reality. Other common symptoms include a drop in blood pressure upon sitting or standing, fainting spells, occasional unresponsiveness, incontinence, constipation or changes in body temperature.

How is Lewy body dementia diagnosed?

There’s no single medical test to diagnose Lewy body dementia. Doctors generally use a combination of medical history and physical examination, plus neuropsychological testing to assess thinking, memory and mood. A brain imaging test called a dopamine transporter scan may be done. In some people with Lewy body dementia, the test may show a decreased amount of the neurochemical dopamine in certain regions of the brain. That change is not seen in Alzheimer’s disease. Most often, if MRI scans of the brain are done, it is to rule out other possible causes of the symptoms. MRI scans often show that people with Lewy body dementia have less damage to an area involved in memory called the hippocampus than people with Alzheimer’s.

There have been some improvements in diagnostic methods based on biomarkers (molecules found in the body that can reveal potential or emerging diseases). With recent advances in skin biopsies and spinal fluid testing, doctors are much closer to being able to give patients a more definitive diagnosis. James Leverenz, M.D., director of the Lou Ruvo Center for Brain Health at the Cleveland Clinic, and his colleagues use spinal fluid tests to help determine whether a patient has Alzheimer’s or Lewy body dementia. Leverenz hopes that these developments will eventually lead to blood tests “to screen people and actually treat them before they develop symptoms.”

When it comes to diagnosing dementia with Lewy bodies or Parkinson’s disease dementia, Maria Eriksdotter, M.D., a professor and senior consultant in geriatric medicine at Karolinska Institutet and Karolinska University Hospital in Stockholm, says the two diseases can look indistinguishable. She is the director of the Swedish national quality registry of dementia disorders and has seen the same patient diagnosed with Parkinson’s disease dementia by one doctor and dementia with Lewy bodies by another. The distinction between them mainly lies in the timing of cognitive and motor symptoms, which has been known as the “one-year rule.”

In Parkinson’s disease dementia, motor symptoms (such as slowness, stiffness, tremor, walking difficulty) occur at least a year before dementia onset. In dementia with Lewy bodies, cognitive issues appear first, and motor symptoms—if they occur—happen later or at the same time as the dementia.

Compared with people who have Alzheimer’s, those with Lewy body dementia “progress faster, have shorter survival, and [cause] more caregiver burden,” says Melissa Armstrong, M.D., professor of neurology and director of the Mangurian Clinical-Research Headquarters for Lewy Body Dementia at the University of Florida in Gainesville. People live an average of five to seven years after diagnosis, according to the National Institute on Aging, although the timespan can range from two to 20 years.

What treatments are available?

Treatments for Lewy body dementia focus on symptom management. Medicines such as cholinesterase inhibitors, also used in Alzheimer’s disease, can help with thinking and memory problems and are often prescribed for Lewy body dementia. For movement issues, doctors may prescribe drugs such as levodopa used to treat Parkinson’s disease, but these medications need to be used carefully because they can sometimes worsen mood or behavioral symptoms, such as hallucinations. Patients with Lewy body dementia are highly sensitive to antipsychotic medications, which can exacerbate movement symptoms, increase agitation or cause severe side effects. It’s important to work with specialists experienced in caring for people with Lewy body dementia for careful monitoring for medication effects.

Other treatments for mood (depression, anxiety), hallucinations, sleep and blood pressure may be helpful. Certain nonmedication therapies, including speech therapy, occupational therapy, physical therapy and exercise, may improve quality of life and function. Additionally, social and emotional support and counseling for the patient and caregiver may help with coping and management.

It’s not uncommon for people who are ultimately diagnosed with dementia with Lewy bodies to have already been seeing different doctors for many different symptoms, Armstrong says. For instance, they might be constipated or get lightheaded when they stand up or have trouble walking in addition to having thinking problems and acting out their dreams at night. When they finally get the diagnosis, “suddenly it’s like, ‘oh, this actually explains a lot,’ ” she says. Not only can it be a relief to understand what’s happening, but it’s also important to be able to involve and coordinate multiple providers, and to prepare for the future.

By understanding the symptoms and challenges, patients and caregivers can more readily navigate this complex disease and get the resources they need. “Even though people don’t want this diagnosis,” Armstrong adds, “if they have it, they want to know what’s coming.”

Researchers are doing clinical studies to develop more effective treatments, in hopes of slowing down or preventing the disorder.

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Marah Stets is a health, lifestyle and food writer based in the Washington, D.C., area. She wrote about traumatic brain injury for AARP.

Jennifer G. Goldman, M.D., is a movement disorders neurologist with specialty certification in behavioral neurology and neuropsychiatry in Chicago, Illinois.