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The Difference Between Lewy Body Dementia, Parkinson’s Disease and Alzheimer’s Disease


The Difference Between Lewy Body Dementia, Parkinson’s Disease and Alzheimer’s Disease

Lewy Body Dementia: A Common Yet Underdiagnosed Dementia

While it’s not a household word yet, Lewy body dementia (LBD) is not a rare disease. It affects an estimated 1.4 million individuals and their families in the United States. Because LBD symptoms can closely resemble other more commonly known disorders like Alzheimer’s disease and Parkinson’s, it is often underdiagnosed or misdiagnosed. In fact, many doctors or other medical professionals still are not familiar with LBD.

What is Lewy Body Dementia?

Lewy body dementia is not a single disorder but rather a spectrum of closely-related disorders involving disturbances of cognition, behavior, sleep, movement and autonomic function.

In these progressive disorders, Lewy bodies (abnormal deposits of a protein called alpha-synuclein) build up in the brain. Lewy bodies in the brain stem cause a disruption in the production of chemical messengers (neurotransmitters) called dopamine. Too little dopamine can cause parkinsonism, a clinical syndrome that’s characterized by tremor, bradykinesia (slow movement), rigidity and postural instability. Parkinsonism can be caused by Parkinson’s disease itself as well as by other underlying neurological conditions such as LBD.  These Lewy bodies are also found throughout other areas of the brain, including the cerebral cortex. The neurotransmitter acetylcholine is also depleted, causing disruption of perception, thinking and behavior.

A German neurologist, Friederich H. Lewy, first discovered the abnormal protein deposits (later named Lewy bodies) in the early 1900s as he was conducting research on Parkinson’s disease.

What’s the Difference Between Lewy Body Dementia, Parkinson’s Disease and Alzheimer’s Disease?

Lewy body dementia is an umbrella term for two related clinical diagnoses: “dementia with Lewy bodies” and “Parkinson’s disease dementia.” These disorders share the same underlying changes in the brain and very similar symptoms, but the symptoms appear in a different order depending on where the Lewy bodies first form.

Dementia with Lewy bodies (DLB) is a type of dementia that causes problems with memory and thinking abilities that are severe enough to interfere with everyday activities. It specifically affects a person’s ability to plan and solve problems, called executive function, and their ability to understand visual information. Dementia always appears first (or around the same time as parkinsonism) in DLB. The motor symptoms of Parkinson’s such as tremor, slowness, stiffness and walking/balance/gait problems usually become more evident as the disease progresses. Visual hallucinations, REM sleep behavior disorder, fluctuating levels of alertness and attention, mood changes and autonomic dysfunction are also characteristic of DLB.

In contrast, Parkinson’s disease dementia (PDD) is a term used for dementia that develops after several or many years of living with Parkinson’s, a disease that is caused by loss of dopamine-producing nerve cells. In nearly all cases of Parkinson’s, people experience motor symptoms in the early stages; some may also have very mild changes in cognition at diagnosis. Over time, non-motor symptoms of Parkinson’s may appear, including cognitive impairment, REM sleep disorder, memory problems, fatigue, anxiety, autonomic dysfunction, pain and more. Most importantly, not all people with Parkinson’s will develop dementia and at this time, it’s impossible to predict which individuals with Parkinson’s will also develop Parkinson’s disease dementia.

Finally, Alzheimer’s is characterized by different abnormal clumps called amyloid plaques, and jumbled fiber bundles called tau tangles. These microscopic structural changes in the brain were discovered by Dr. Alois Alzheimer in 1906. These plaques and tangles, together with loss of connections between nerve cells, contribute to loss of coherence and memory, as well as a progressive impairment in conducting normal activities of daily living.

Alzheimer’s disease is associated with a lack of acetylcholine, a neurotransmitter in both the peripheral nervous system (PNS) and central nervous system (CNS). Damage initially occurs in the hippocampus, a part of the brain that is involved in memory formation. Other portions of the brain, such as the temporal, parietal and frontal cortices, are progressively affected in those with Alzheimer’s disease.

In comparison, people with dementia with Lewy bodies (DLB) may first present with REM sleep behavior disorder years or even decades before developing dementia, or they may experience visual hallucinations early in the course of their dementia. These are features that help differentiate DLB from Alzheimer’s, even in the early stage of dementia.

Download this free brochure from the Lewy Body Dementia Association to see a comparison chart of the symptoms of LBD, Parkinson’s and Alzheimer’s disease.

Lewy Body Comparison Chart

What Causes Lewy Body Dementia?

The causes of LBD are not yet well understood, but research is ongoing in this area. There are probably multiple factors involved, including genetic and environmental risk factors that combine with natural aging processes to make someone susceptible to LBD.

For more information, visit www.lbda.org.

Modified with permission from the Lewy Body Dementia Association

To learn more about motor symptoms related to Parkinson’s, visit here.

To learn more about non-motor symptoms related to Parkinson’s, visit here.

10 Comments on “The Difference Between Lewy Body Dementia, Parkinson’s Disease and Alzheimer’s Disease

    • Larry blocker

      July 17, 2018 at 12:48 pm Reply

      I had never heard of lewy bodies dementhia until my wife gor it. We need to do more research on it and provide more information to the public.

      • Alex Reinhardt

        July 24, 2018 at 1:27 pm Reply

        Thanks for commenting, Larry. We hope that by creating content on the topic, our community will become more informed and fewer people will be misdiagnosed.

    • Elaine SooHoo

      July 18, 2018 at 7:26 pm Reply

      It is my understanding that not all Lewy body patients develop Parkinson’s, but that if an autopsy of a Parkinson’s brain does not show Lewy bodies, then it wasn’t Parkinson’s.

      • Melani Dizon

        July 25, 2018 at 11:45 am Reply

        Hi Elaine – I’m not sure if that’s the case; however, you may be able to find some answers about that from the LBDA. Here’s an article on their site that includes questions from caregivers that may be of interest to you: https://www.lbda.org/go/caregiver-faq.

    • ClayR

      August 3, 2018 at 8:54 pm Reply

      There seems to be greater confusion between Lewy Body Dementia and Parkinson’s Disease due to tv ads (the other side of Parkinson’s). Here recently Alan Alda said he decided to get tested for Parkinson’s due to “cutting edge” research suggesting REM sleep disturbances tend to be precursors to Parkinson’s. However, as in the article above mentions REM sleep disturbances have long been known as a key early sign of Lewy Body Dimentia. Is this confusion due to doctors lack of knowledge about Lewy Body Dementia, confusion in the terminology or a struggle for funding?

      As a former caregiver of someone with Lewy Bodies it’s disturbing to see such confusion. There seemed to have been a ray of light from Robin William’s wife for educating the medical establishment. I remember doing my own research to figure out what was wrong with my loved one in a medical text book. There was a whole chapter on Alzheimer’s, seven pages on Parkinson’s disease and only three paragraphs on Lewy Body.

      • Melani Dizon

        August 6, 2018 at 2:15 pm Reply

        Hi Clay,
        Thank you for your comment. There is a lot of confusion and TV ads never seem to clear it up, as you suggest. I also think that this could very well be confusion on the part of doctors about Lewy Body Dementia as well. The reality is, there are many doctors who end up treating people with LBD, PD and AD and they are not specialists. They are GPs and for better or worse, they are the person’s only option for care where they live. The doctors do the best they can but these are very complicated diseases and even specialists sometimes struggle to parse out all of the symptoms. The other challenge and is that everyone with Parkinson’s presents differently and the timing of certain symptoms has an impact on diagnosis and treatment. You’re not alone in thinking this way, and it’s one of the reasons we wanted to write about it. People were searching for Lewy Body Dementia on our site, and we wanted to create content to help distinguish between these three diseases. And also let people know that there is a great association, the Lewy Body Dementia Association to look to for more information. Hopefully calling attention to the confusion will continue to keep the conversation top of mind.

    • Theresa

      August 17, 2018 at 6:19 pm Reply

      I was wondering if anyone is doing research on the genetic implications of having one parent with Alzheimer disease and the other with Parkinson’s.
      I have one daughter with MS as well. Seems to me that they could all be related either genetically or environmentally.

    • Carol Gober

      August 21, 2018 at 7:51 pm Reply

      At first my husband was diagnose with PD about 4 months ago but after researching on what I saw everyday that the doctors did not see, I knew that something else was going on. Yes he had memory loss unstable when walking and shaking . Why could he not step up on curb or not speak or hold his silverware to eat ? These symptoms may only last 30 minutes to a hour at a time it did not make since to me, so I kept after doctors. Would take him in to doctors office when it was happening a lot of the time even though it might be over before we got there. It became very overwhelming on my part and frustrating I started keeping notes of what was going on with him, times, symptoms how long it went on and thats when we got a true diagnosis LBD with PD. He has started medications and is much better we are taking each day at a time even though symptoms come up like just this morning I came back from store and he could not speak . He was pointing to his mouth and shaking his head. I knew right away so just explained it was the LBD , poke some fun at him told him he could not give me hell for going to store. lol . I made coffee and began telling him about my trip to store after awhile he was able to make some noises soon after we were talking just like nothing happen. It is my advice to anyone reading this , research and keep notes it can really help doctors give a true diagnose .

      • Melani Dizon

        August 22, 2018 at 7:53 am Reply

        Thank you for sharing your story, Carol. It sounds like your husband has an amazing care partner in you. I love that the two of you have found a way to bring some levity to a very serious and life-changing situation. I’m sure others will find a great deal of inspiration (and some great ideas) from what you’ve shared. Every victory counts!

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