Health Topic

Lewy Body Dementia

Lewy body dementia (LBD) is one common cause of dementia. In LBD, protein deposits build up in the brain. Read about the symptoms and what can help.

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Also called: Dementia with Lewy bodies · LBD · Lewy body disease · Parkinson's disease dementia

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Lewy Body Dementia

Lewy body dementia (LBD) is one of the most common types of dementia in older adults. Dementia is a loss of mental functions that is severe enough to affect your daily life and activities. These functions include:

  • Memory
  • Language skills
  • Visual perception (your ability to make sense of what you see)
  • Problem solving
  • Trouble with everyday tasks
  • The ability to focus and pay attention

There are two types of LBD: dementia with Lewy bodies and Parkinson's disease dementia.

Both types cause the same changes in the brain. And, over time, they can cause similar symptoms. The main difference is in when the cognitive (thinking) and movement symptoms start.

Dementia with Lewy bodies causes problems with thinking ability that seem similar to Alzheimer's disease. Later, it also causes other symptoms, such as movement symptoms, visual hallucinations, and certain sleep disorders. It also causes more trouble with mental activities than with memory.

Parkinson's disease dementia starts as a movement disorder. It first causes the symptoms of Parkinson's disease: slowed movement, muscle stiffness, tremor, and a shuffling walk. Later on, it causes dementia.

LBD happens when Lewy bodies build up in parts of the brain that control memory, thinking, and movement. Lewy bodies are abnormal deposits of a protein called alpha-synuclein. Researchers don't know exactly why these deposits form. But they do know that other diseases, such as Parkinson's disease, also involve a build-up of that protein.

The biggest risk factor for LBD is age; most people who get it are over age 50. People who have a family history of LBD are also at higher risk.

LBD is a progressive disease. This means that the symptoms start slowly and get worse over time. The most common symptoms include changes in cognition, movement, sleep, and behavior:

  • Dementia, which is a loss of mental functions that is severe enough to affect your daily life and activities
  • Changes in concentration, attention, alertness, and wakefulness. These changes usually happen from day to day. But sometimes they can also happen throughout the same day.
  • Visual hallucinations, which means seeing things that are not there
  • Problems with movement and posture, including slowness of movement, difficulty walking, and muscle stiffness. These are called parkinsonian motor symptoms.
  • REM sleep behavior disorder, a condition in which a person seems to act out dreams. It may include vivid dreaming, talking in one's sleep, violent movements, or falling out of bed. This may be the earliest symptom of LBD in some people. It can appear several years before any other LBD symptoms.
  • Changes in behavior and mood, such as depression, anxiety, and apathy (a lack of interest in normal daily activities or events)

In the early stages of LBD, symptoms can be mild, and people can function fairly normally. As the disease gets worse, people with LBD need more help due to problems with thinking and movement. In the later stages of the disease, they often cannot care for themselves.

There isn't one test that can diagnose LBD. It is important to see an experienced doctor to get a diagnosis. This would usually be a specialist such as a neurologist. The doctor will:

  • Do a medical history, including taking a detailed account of the symptoms. The doctor will talk to both the patient and caregivers.
  • Do physical and neurological exams
  • Do tests to rule out other conditions that could cause similar symptoms. These could include blood tests and brain imaging tests.
  • Do neuropsychological tests to evaluate memory and other cognitive functions

LBD can be hard to diagnose, because Parkinson's disease and Alzheimer's disease cause similar symptoms. Scientists think that Lewy body disease might be related to these diseases, or that they sometimes happen together.

It's also important to know which type of LBD a person has, so the doctor can treat that type's particular symptoms. It also helps the doctor understand how the disease will affect the person over time. The doctor makes a diagnosis based on when certain symptoms start:

  • If cognitive symptoms start within a year of movement problems, the diagnosis is dementia with Lewy bodies
  • If cognitive problems start more than a year after the movement problems, the diagnosis is Parkinson's disease dementia

There is no cure for LBD, but treatments can help with the symptoms:

  • Medicines may help with some of the cognitive, movement, and psychiatric symptoms
  • Physical therapy can help with movement problems
  • Occupational therapy may help find ways to more easily do everyday activities
  • Speech therapy may help with swallowing difficulties and trouble speaking loudly and clearly
  • Mental health counseling can help people with LBD and their families learn how to manage difficult emotions and behaviors. It can also help them plan for the future.
  • Music or art therapy may reduce anxiety and improve well-being

Support groups can also be helpful for people with LBD and their caregivers. Support groups can give emotional and social support. They are also a place where people can share tips about how to deal with day-to-day challenges.

It sits within Brain and Nerves.

The lead U.S. institute for this subject is the National Institute of Neurological Disorders and Stroke.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Lewy Body Dementia

252 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Symptoms

Diagnosis and Tests

Treatments and Therapies

Living With

Genetics

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Lewy Body Disease. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Lewy Body Dementia, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.