What Is Lewy Body Dementia?

Medically Reviewed by Christopher Melinosky, MD on June 07, 2021
4 min read

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. These problems can keep you from doing everyday tasks or taking care of yourself, a condition called dementia.

Lewy body dementia (LBD) is one of the most common types of dementia, after Alzheimer’s disease. It usually happens to people who are 50 or over. There are two types:

  • 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.

These diseases are similar in a lot of ways. But there are some key differences in the symptoms that affect people with LBD and when those symptoms happen.

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 someone has 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.

LBD and Parkinson’s disease both cause movement problems, like 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.

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 makes Lewy bodies start to build up in the brain. They’re also not sure why some people get LBD and others don’t.

Some health conditions worsen your odds of getting the condition. People with Parkinson’s disease or REM sleep behavior disorder have a higher risk of LBD.

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, multitasking, planning, organizing, or remembering
  • Losing concentration
  • Staring into space
  • Hallucinations


  • Shuffling or slow walk
  • Balance problems or falling a lot
  • Stiff muscles
  • Tremors or shaking hands
  • Stooped posture


  • 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 thinking a relative or friend is an imposter 

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:

  • Ask you about your medical history and do a physical exam
  • Blood tests that check the levels of hormones or vitamins in your body. The wrong amounts can cause other types of dementia.
  • CT scan or MRI scan of your brain to spot changes caused by other dementias
  • Tests to measure your memory, language skills, or thinking ability

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 make some symptoms, such as hallucinations, trouble moving, or thinking problems, much worse. 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. They 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.


Organizations like 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.