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Lewy Body Dementia
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Brain Nerves

Lewy Body Dementia

Lewy body dementia is a progressive condition characterized by the buildup of abnormal protein deposits in the brain, affecting memory, movement, and behavior.

What is Lewy body dementia (LBD)?

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

What are the types of Lewy body dementia (LBD)?

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.

What causes Lewy body dementia (LBD)?

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.

Who is at risk for Lewy body dementia (LBD)?

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.

What are the symptoms of Lewy body dementia (LBD)?

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.

How is Lewy body dementia (LBD) diagnosed?

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.

What are the treatments for Lewy body dementia (LBD)?

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.

Frequently Asked Questions

While both conditions involve cognitive decline, Lewy body dementia (LBD) often presents with distinct early signs that differ from Alzheimer's. In LBD, patients frequently experience vivid visual hallucinations, such as seeing people or animals that are not there, and have significant fluctuations in attention and alertness, where they may appear confused or drowsy one moment and clear the next. Additionally, movement problems similar to Parkinson's disease, such as shuffling gait or muscle stiffness, often appear early in LBD, whereas they are typically a late-stage symptom in Alzheimer's.
Patients with LBD are highly sensitive to antipsychotic medications, particularly typical antipsychotics and some atypical ones. Using these drugs can cause severe, sometimes irreversible, worsening of movement symptoms, increased confusion, and a heightened risk of falls. In some cases, this sensitivity can be life-threatening. If behavioral symptoms like agitation or hallucinations become severe, clinicians must carefully select medications that are safer for LBD, such as low-dose atypical antipsychotics with specific monitoring, or non-drug interventions.
REM sleep behavior disorder (RBD) is a very common early sign of LBD, where individuals physically act out their dreams, which can include punching, kicking, or falling out of bed. This poses a safety risk to the patient and bed partners. Other sleep issues include excessive daytime sleepiness and disrupted sleep-wake cycles. Managing RBD often involves creating a safe sleep environment, removing sharp objects, and using weighted blankets or protective gear, while medication adjustments may be necessary to reduce dream enactment.
LBD often causes visual-spatial difficulties, making it hard for patients to judge distances, recognize faces, or navigate familiar spaces. They may struggle with tasks like cooking, driving, or finding their way around the house. To manage this, caregivers can simplify the environment by reducing clutter, using high-contrast colors to distinguish objects, and ensuring adequate lighting. It is also important to avoid forcing the patient to perform complex visual tasks and to provide clear, simple instructions one step at a time.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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