What is Lewy Body Dementia? 5 Main Symptoms

Find out what lewy body dementia is and how it’s different from Alzheimer’s and Parkinson’s

Get the facts about Lewy body dementia

Lewy body dementia is a progressive, degenerative brain disease. It’s the third most common type of dementia, after Alzheimer’s and vascular dementia.

It can be a confusing type of dementia because some symptoms are similar to those found in Alzheimer’s, but loss of short-term memory isn’t common.

It can also be challenging to diagnose because some of the symptoms are similar to Parkinson’s disease.

We explain what Lewy body dementia is, how it’s different from Alzheimer’s and Parkinson’s, and the 5 main symptoms of the disease.




What is Lewy body dementia?

It’s called Lewy body dementia because the disease is associated with clumps of protein found in the brain called Lewy bodies.

When they build up, they cause problems with the way the brain works, including memory, movement, thinking skills, mood, and behavior.

There are two forms of Lewy body, dementia with Lewy bodies and Parkinson’s disease dementia.

In dementia with Lewy bodies, the first symptoms are like the memory disorders seen in Alzheimer’s. Later, the person will develop movement problems and other Lewy body symptoms.

In Parkinson’s disease dementia, the person first develops a movement disorder that looks like Parkinson’s, but later develops dementia symptoms. Their physical symptoms may also be milder than in typical Parkinson’s.


How Lewy body dementia is different from Parkinson’s or Alzheimer’s

Lewy body dementia is similar to and often confused with Parkinson’s or Alzheimer’s. But there are some differences in the symptoms and when those symptoms happen.

Lewy body may not cause short-term memory loss that happens with Alzheimer’s. In Lewy body, problems with thinking, alertness, and paying attention will come and go. 

A sign that your older adult could have Lewy body rather than another dementia is if they have symptoms of cognitive decline without the typical short-term memory problems.

For example, Lewy body often causes hallucinations, especially in the first few years. With Alzheimer’s, hallucinations usually don’t show up until the later stages.

People with Lewy body also have REM sleep behavior disorder, which causes them to act out their dreams and make violent movements while asleep. This is not common in Alzheimer’s.

Both Lewy body and Parkinson’s cause problems with movement, but Parkinson’s doesn’t cause problems with thinking and memory until the later stages of the disease – and sometimes it doesn’t happen at all. With Lewy body, the cognitive problems start much sooner.

Because of these differences, the treatments and medications used for Lewy body dementia are not always the same as the ones used to treat Parkinson’s or Alzheimer’s.




5 main symptoms of Lewy body dementia

There are 5 groups of symptoms that are common in Lewy body dementia. They will get worse over time, usually over several years.

1. Cognitive impairment

  • Extreme swings between being alert and being confused or drowsy – episodes are unpredictable and could last a few seconds to several hours
  • Reduced attention span
  • Difficulty with planning, decision-making, organization
  • Problems with visual perception (judging and navigating distances) – often causing falls or getting lost in familiar places
  • Increased trouble with the tasks of daily living

2. Visual hallucinations
Repeated visual hallucinations or delusions are also common – like seeing shapes, colors, people, or animals that aren’t there. They may also have conversations with people who are deceased.

3. Problems with movement

  • Slow movement
  • Shuffling walk or abnormal gait
  • Stiff limbs
  • Tremors
  • Lack of facial expression

4. Sleep disturbances

  • Insomnia
  • Daytime sleepiness
  • REM sleep behavior disorder – acting out dreams while asleep: physically moving, sleep talking, screaming, hitting, or even getting up and engaging in daytime activities

5. Fluctuations in autonomic processes
Lewy body may also cause problems with bodily functions that are automatic, including blood pressure, body temperature, urination, constipation, and swallowing.


Life expectancy with Lewy body

The average person usually lives 5 to 7 years after the disease starts and they usually die of pneumonia or other illness.

Unlike other dementias, Lewy body doesn’t follow a pattern of stages. The disease will continue to get worse over time, but the rate of decline is different in each person.


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By DailyCaring Editorial Team


  • Reply October 18, 2017

    Gloria Denton

    I really wish you wouldn’t add life expectancy in your articles. It is very painful to have it pop up unexpectantly. I am a wife who’s much younger than my beloved husband who has just been diagnosed. Watching the calendar has taken away any sense of hopefulness I had. I am already suffering from major depression. Also, every other reputable article I have read says Dementia with Lewy Bodies is the second most common dementia. Suicidial ideation in the south.

    • Reply October 18, 2017


      I’m very sorry 🙁 It is certainly sad to think about the potential end of life for the people we love. But sometimes knowing what to expect can help us to maximize the time we have left and enjoy it as much as possible.

      If you are feeling suicidal, I urge you to call the National Suicide Prevention Hotline at 1-800-273-8255 — https://suicidepreventionlifeline.org/

      I hope that you’re able to speak with someone who can help ease your depression. Caregiving is a stressful and challenging role, which can often lead to depression. A therapist can often teach helpful ways to cope with the stress and anticipatory grief or identify when medication may also be helpful. We have some recommendations on how to find low-cost therapy options — http://dailycaring.com/low-cost-therapy-options-help-caregivers-cope/

      Support groups are another wonderful way to get support from people who understand what you’re going through and find ways to cope with what’s happening. Both in-person and online support groups are wonderful. Here are some recommendations:

      You may also want to contact the Alzheimer’s Association and speak with one of their wonderful family specialists. They may be able to recommend helpful local resources. Call them 24/7 at 1-800-272-3900.

      In terms of how common Lewy Body dementia is, we look to experts like Alzheimer’s Association and the U.S. National Institute on Aging who say that it’s the third most common form after Alzheimer’s and vascular dementia. Regardless, it’s a serious condition that affects far too many people 🙁

  • Reply August 5, 2017


    My mother has Alzheimer’s and uf something happens, she will say someone did what ever happen. She will say someone has been mean to her, and she wants to stack paper towels up. And she has to have at least 5 rools of toilet paper in the bathroom. But she accuses other people of doing things. What makes her do this.

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