What Is Lewy Body Dementia?

Medically Reviewed by Zilpah Sheikh, MD on January 24, 2024
9 min read

Lewy body dementia (LBD) is one of the most common types of dementia, after Alzheimer’s disease. It usually affects people aged 50 or older.

Lewy bodies are clumps of protein that can form in the brain. When they build up, they can cause problems with the way your brain works, including your memory, movement, thinking skills, mood, and behavior.

There are two types of LBD:

  • Dementia with Lewy bodies often starts when you have a hard time moving your body. Within a year, you start to have thinking and memory problems that are similar to Alzheimer’s disease, along with changes in behavior. You also might see things that aren’t there, called hallucinations.
  • Parkinson’s disease dementia first causes movement problems. Trouble with memory happens much later in the disease.

Right now, there’s no cure for Lewy body dementia. But there are ways to ease symptoms for a while. Scientists are also getting better at understanding the differences between LBD and other conditions.

Lewy body dementia vs. Alzheimer’s

These diseases are similar in a lot of ways, but there are some key differences in their symptoms and the timing of symptom onset.

LBD may not cause short-term memory loss like Alzheimer’s. People with both conditions have trouble with thinking, alertness, and paying attention. But in LBD, those problems come and go. The disease can also cause hallucinations, often in the first few years of LBD. People with Alzheimer’s usually don’t have hallucinations until the later stages.

People with LBD also often act out their dreams and make violent movements when they’re asleep. It’s called REM sleep behavior disorder. Sometimes, it’s the first sign that someone has LBD.

Lewy body dementia vs. Parkinson’s

LBD and Parkinson’s disease both cause movement problems, such as stiff muscles and tremors. But most people with Parkinson’s don’t have problems with their thinking and memory (dementia) until the very later stages of their disease. Sometimes, they don’t have it at all. In the type of LBD known as Parkinson’s disease with dementia, these problems begin much sooner.

People with LBD also need different drugs for their condition than the ones that treat Parkinson’s or Alzheimer’s.

How common is LBD?

LBD affects more than 1.4 million people in the U.S. It makes up about 5% of dementia cases in older people.

Lewy bodies, named after the scientist who discovered them, are made of a protein called alpha-synuclein. When they build up, they keep your brain from making the right amount of two important chemicals. One of them, called acetylcholine, affects your memory and learning. The other, called dopamine, affects how you move, your mood, and your sleep.

Scientists aren’t sure what causes the buildup of Lewy bodies in the brain. They’re also not sure why some people get LBD and others don’t. Research is underway to help doctors better understand the disease and its causes.

Is Lewy body dementia hereditary?

LBD is not considered a hereditary disease. But if you have a family member with it, your chance of developing the disease goes up. Also, certain changes in the genes APOE, SNCA, and GBA have been linked to a higher risk of LBD. 


Some risk factors for LBD are:

  • Older age
  • Other health conditions, such as Parkinson’s disease and REM sleep behavior disorder
  • A family history of the disease
  • Being assigned male at birth (AMAB)

Not everyone will have the same warning signs. They often depend on the type of LBD you have. They might be mild or get worse at times.

Like other types of dementia, LBD causes changes in your thinking, mood, behavior, movement, and sleep. Symptoms include:

Thinking skills

  • Trouble making decisions, judging distances, paying attention, multitasking, planning, organizing, or remembering
  • Losing concentration
  • Staring into space
  • Hallucinations
  • Ideas that are illogical, unclear, or disorganized
  • Poor judgment
  • Confusion about time or where you are
  • Trouble with numbers or language


  • Shuffling or slow walk
  • A frozen stance
  • Balance problems or falling a lot
  • Stiff muscles
  • Tremors or shaking hands
  • Stooped posture
  • Loss of coordination
  • Smaller handwriting than usual
  • Trouble swallowing
  • Reduced facial expression
  • A weak voice


  • REM sleep behavior disorder (acting out dreams, including making violent movements during sleep or falling out of bed)
  • Sleeping a lot during the daytime (as much as 2 hours every day)
  • Trouble falling or staying asleep
  • The urge to move your legs when you’re at rest, called restless legs syndrome


  • Depression or lack of interest
  • Anxiety
  • Delusions, such as believing a relative or friend is an imposter
  • Agitation or irritability
  • Restlessness
  • Paranoia, such as a suspicion that people are out to get you 
  • Unusual behaviors, such as pacing, hand-wringing, or repeating words or phrases

Other symptoms

LBD can affect a part of your nervous system that regulates the way your heart, glands, and muscles work. This can cause:

  • Body temperature changes
  • Dizziness or fainting
  • Blood pressure problems
  • Sensitivity to hold and cold
  • Urinary incontinence (loss of bladder control)
  • Sexual dysfunction
  • Constipation
  • A weakened sense of smell

What are the first signs of Lewy body dementia?

Hallucinations are often the first sign of LBD. They affect about 80% of people with the disease.

Some other early symptoms include:

  • Changes in how you think and solve problems
  • Forgetfulness
  • Sleep issues
  • Movement difficulties
  • Behavior or mood changes

Lewy body dementia hallucinations

Lewy body hallucinations may cause you to see things that aren’t really there. You may see animals, shapes, or people. Though less common, it’s also possible to hear, smell, or taste things that aren’t there.

Lewy body dementia crying

People with LBD may have episodes of uncontrollable crying or laughter, which doctors call a pseudobulbar affect (PBA). With PBA, the crying and laughter are involuntary and don’t usually reflect how the person with LBD is feeling.

Lewy body dementia posture

People with LBD may have a stooped posture. This means your shoulders appear rounded when you walk. A stooped posture can cause you to look hunched over.

Doctors have classified LBD into these seven stages:

  • Stage I: No cognitive decline. Symptoms are not noticeable to the patient, doctors, or loved ones.
  • Stage II: Very mild cognitive decline. Slight changes, such as forgetfulness, may crop up.
  • Stage III: Mild cognitive decline. Symptoms may become clearer to loved ones. In this stage, people with LBD may have mild memory loss, forgetfulness, and concentration problems.
  • Stage IV: Moderate cognitive decline. At this point, the person with LBD has obvious forgetfulness and difficulty performing daily tasks. Many patients are diagnosed at stage IV.
  • Stage V: Moderately severe cognitive decline. In this stage, people with LBD have significant memory problems and may require assistance with certain tasks.
  • Stage VI: Severe cognitive decline. In this stage, memory loss is significant. Many patients have a change in personality, lose their ability to speak, and struggle with incontinence. They need lots of support to live well.
  • Stage VII: Very severe cognitive decline. People lose their ability to communicate and may not be able to walk. They need extensive assistance. Stage VII usually lasts 1.5-2.5 years.

There is no one test that can diagnose LBD. Because it’s similar to other types of dementia, it’s hard for doctors to identify it, especially in the early stages. So they often try to rule out other health problems that might cause the same symptoms.

Your doctor might do a few tests, including:

  • A physical exam
  • A neurological exam to test your reflexes, strength, muscle tone, walking, eye movements, balance, and sense of touch
  • Blood tests that check the levels of hormones or vitamins in your body. The wrong amounts can cause other types of dementia.
  • A CT scan or an MRI scan of your brain to spot changes caused by other dementias. Other special scans, such as positron emission tomography (PET), fluorodeoxyglucose PET, or single-photon emission computerized tomography (SPECT) may be done to get a better look at the brain.
  • Tests to measure your memory, language skills, or thinking ability
  • Sleep tests to check for REM sleep behavior disorder or other problems
  • Heart test to check the blood flow to your heart

Right now, there aren’t any drugs that can stop or reverse Lewy body dementia. But medications can help relieve your symptoms for a few months. These drugs include:

Some drugs, called neuroleptic or antipsychotic medicines, can treat severe hallucinations or behavior problems for people with Alzheimer’s, but they’re often not good for people with LBD. They can worsen some symptoms, such as hallucinations, trouble moving, or thinking problems. If you need these drugs, your doctor will have to watch you very carefully for bad side effects. Besides medications, you can do other things to ease your LBD symptoms:

  • Physical therapy can guide you through exercises that can improve your movements and balance.
  • If you’re depressed, anxious, or have other mood problems, consider counseling or psychotherapy. These options can help you find ways to handle your emotions. Support groups also are great ways to connect with others who live with LBD.
  • Occupational therapy can help you learn easier ways to handle tasks that are hard to do with LBD.

A person with LBD can benefit from a care team of professionals, such as a:

  • Primary care doctor
  • Neurologist who focuses on dementia or movement disorders
  • Physical, speech, or occupational therapist
  • Mental health expert
  • Palliative care specialist who can help provide end-of-life supportive care

Organizations such as the Lewy Body Dementia Association or the Alzheimer’s Association can give you more information about dementia and direct you to resources in your area, too.

New treatment for Lewy body dementia

Researchers are testing several novel therapies to help Lewy body dementia. For example, the drugs nilotinib and neflamapimod have shown promise in clinical trials.

How to find clinical trials for LBD

Clinical trials help scientists learn about different diseases and test new treatments. Some organizations that provide information about clinical trials for LBD are:

  • Alzheimers.gov
  • Lewy Body Dementia Association
  • ClinicalTrials.gov

If you find a study near you, contact the study coordinator to see if you or your loved one may qualify.

As symptoms worsen, LBD can lead to other problems. Some possible complications include:

  • Aggressive behaviors
  • Severe dementia
  • Depression
  • Falling or other injuries
  • Tremors
  • Death

Living with LBD can be a challenge for both patients and their caregivers. Here are some ways to cope:

  • Create a support network. Family and close friends can provide help if you need it. They can also listen to your concerns. You may also benefit from talking with a mental health professional or a spiritual advisor. As the disease advances, you may need to find a professional caregiver.
  • Take safety measures. If you struggle with thinking or have movement problems, you may need to take extra steps to protect yourself. A medical alert service allows you to call 911 with the push of a button. Also, be sure to keep your living area free of falling hazards. You may want to install grab bars or ramps to help you get around.
  • Plan ahead. Tell your family and doctors about your care and financial preferences. Look for services, such as nursing care or home care, before you need them. It’s also a good idea to talk to a lawyer who can help you write or update your will and other important documents.
  • Enjoy yourself. Participate in activities that bring you joy and pleasure.

Lewy body dementia life expectancy

The average life expectancy for someone with LBD is around 7-8 years after symptoms begin. But, a person’s outlook can vary quite a bit. Some people with LBD live up to 20 years after a diagnosis.

LBD is a form of dementia that leads to problems with your thinking, mood, movement, behavior, and sleep. Though LBD gets worse over time, you can still live a rewarding life. Ask your doctor about medications, therapies, or other strategies that can lessen your symptoms.

How long do Lewy body dementia patients live?

On average, people with LBD live about 7-8 years after their symptoms start.

What is the root cause of Lewy body dementia?

Scientists don’t know exactly what causes Lewy body dementia. Research is going on to learn more about why LBD affects certain people.

Are people with Lewy body dementia aggressive?

People with LBD can display aggressive behaviors, such as hitting, choking, biting, cursing, or name-calling. If your loved one shows aggression, you should stay calm, provide comfort, and try to address the feelings that triggered the behavior. Get help if they become violent.