Parkinson’s and Lewy Body Dementia: What’s the Difference?
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If you have been diagnosed with Parkinson’s disease (PD), you may have heard of Lewy body dementia (LBD). Are they the same? Are they different? Although PD and LBD may seem very similar in terms of diagnosis, symptoms, and prognosis, there are many important differences between these two conditions.

Let’s start with some major similarities between PD and LBD:

  • Both PD and LBD affect approximately 1 million people in the US.
  • PD and LBD are diseases that affect the nerve cells in the brain.
  • PD and LBD are chronic, progressive diseases: both conditions affect patients over many years, and symptoms tend to become more apparent over time.
  • Although no cure currently exists for PD or LBD, many medications are available to reduce and manage the symptoms of both diseases.
  • There is no single way to diagnosis PD or LBD. Both conditions require a series of tests and examinations to rule out other conditions.
  • PD and LBD patients are usually diagnosed around the age of 60.

What is Parkinson’s disease?

PD is a chronic, neurodegenerative movement disorder. PD affects 1 out of every 100 individuals over the age of 601, and patients commonly experience muscle rigidity, changes in speech and walking, and tremors. Some studies suggest that having PD also increases your risk of developing LBD, but most patients have only one of these conditions.2

What is Lewy body dementia?

LBD is a chronic, neurodegenerative cognitive disorder, and is the 3rd most common form of dementia.3 Unlike most other forms of dementia, people with LBD have Lewy bodies in the brain. Lewy bodies are abnormally-folded proteins found in the nerve cells of the brain.2 Patients with LBD may experience memory/cognitive problems, visual hallucinations, and Parkinsonism symptoms.4

Wait, so what is Parkinsonism?

Parkinsonism refers to the motor symptoms that are typically associated with PD, such as tremors, stiffness, and walking/balance problems. Both PD and LBD are forms of Parkinsonism, meaning that PD patients and LBD patients may experience these motor symptoms.2 Because the Parkinsonism motor symptoms of PD and LBD can be very similar, it can be difficult to differentiate between the two conditions.

Lewy bodies: More than LBD

LBD is characterized by the presence of Lewy bodies in the nerve cells of the brain, meaning that LBD patients have Lewy bodies in the brain.2 However, Lewy bodies are also common with other conditions, such as Alzheimer’s and Parkinson’s Disease. In fact, most people with PD also have Lewy bodies in their brain. However, even if they have Lewy bodies, not all Parkinson’s patients will also develop LBD.2

Is it genetic?

While a small number of PD cases are genetic, LBD is not normally genetic. Some families have a genetic mutation that increases the risk of LBD, but LBD is not typically considered a genetic disease.5 Conversely, about 10-15% of PD cases are genetic.

Is dementia a symptom of both?

One of the biggest similarities between PD and LBD is dementia. Some studies have found that approximately 78% of PD patients will eventually develop dementia.4 More specifically, almost half of Parkinson’s patients will develop a certain type of dementia called Parkinson’s Dementia, usually 10-15 years after their initial PD diagnosis.3 People with Parkinson’s Dementia commonly experience poor memory and concentration, slowed thinking, confusion, depression, emotional changes, delusions, and visual hallucinations.

Parkinson’s dementia is different than LBD, mainly in which symptoms occur first (dementia symptoms or motor symptoms). Patients with Parkinson’s Dementia will first show Parkinson’s motor symptoms, followed by dementia many years after diagnosis. Conversely, LBD patients will first show dementia symptoms and may show motor symptoms later.3

What about me?

Remember, every illness affects every person differently. If you have PD, your symptoms will be both similar and different to other people with PD. Additionally, even though PD and LBD are biologically similar, most PD patients do not have LBD, and vice versa! If you have questions about your PD, talk to your medical provider, check out our other resources, and be sure to connect with your PD community!

view references
  1. Lewy Body Dementia Association. The LBD spectrum. https://www.lbda.org/content/lbd-spectrum. Accessed on April 1, 2017.
  2. Shake It Up Australia Foundation. FAQs on Lewy body dementia. 2015. https://shakeitup.org.au/faqs-on-lewy-body-dementia/. Accessed on April 1, 2017.
  3. Huang J. Lewy body dementia and Parkinson disease dementia. Merck Manual. 2016. http://www.merckmanuals.com/professional/neurologic-disorders/delirium-and-dementia/lewy-body-dementia-and-parkinson-disease-dementia. Accessed on April 1, 2017.
  4. McKeith I, Mosimann, UP. Dementia with Lewy bodies and Parkinson’s disease. Parkinsonism & Related Disorders. 2004;10:S15-S18. doi: 10.1016/j.parkreldis.2003.12.005.
  5. Lewy Body Dementia Association. Causes and risk factors. https://www.lbda.org/content/lbd-booklet/lbd-causes-risk-factors. Accessed on April 1, 2017.
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