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Alzheimer's Disease Health Center

Select An Article

What Is Lewy Body Dementia?

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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

Getting a Diagnosis

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
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