Lewy Bodies, Dementia, and Parkinson’s – What Does it all Mean?

Here are two common scenarios that may sound familiar:

Scenario 1
A patient develops a series of neurologic symptoms, is evaluated by a neurologist and is told that she has Parkinson’s disease (PD). She then visits another neurologist for a second opinion and is told she has Lewy Body Dementia (LBD).

Scenario 2
A patient has his first visit with his neurologist and is told that he has PD, at a subsequent visit the diagnosis is changed to Parkinson’s disease dementia (PDD), and at a follow up visit the diagnosis is changed yet again to Dementia with Lewy Bodies (DLB).

Both of these situations understandably cause great uncertainty and frustration.

Useful definitions

Let us start dissecting this by setting up a short glossary to which you can refer as you read this post. Of note, this terminology is so confusing, that you may find sources that give different definitions! The definitions presented here are the ones adopted by the National Institute on Aging.

  • Dementia – a loss of cognitive functioning significant enough to interfere with daily activities.
  • Lewy body – an abnormal aggregation or clumping of the protein alpha-synuclein, which can be present in the brain in a range of neurologic diseases.
  • Dementia with Lewy Bodies (DLB)– a degenerative neurologic disease marked by a constellation of movement and non-movement symptoms, including dementia, and associated with the presence of Lewy bodies in the brain. In this disease, dementia develops early on in the course of the disease.
  • Parkinson’s Disease (PD) – a degenerative neurologic disease marked by a constellation of movement and non-movement symptoms and associated with the presence of Lewy bodies in the brain. This term does not address specifically whether dementia is among the symptoms.
  • Parkinson’s Disease Dementia (PDD) – dementia that has developed in someone with established PD. The dementia develops later in the course of the disease.
  • Lewy Body Dementia (LBD) – an umbrella term which encompasses DLB and PDD.

“Location, location, location”

This saying implies that the value of real estate is inextricably linked to its locale. The same holds true for brain real estate. Because different parts of the brain control different functions, the same lesion in one part of the brain will cause one set of symptoms and in another part of the brain will cause a different set of symptoms.

Alpha-synuclein buildup

In PD, PDD and DLB, the protein alpha-synuclein abnormally accumulates in the brain in aggregates, or clumps, called Lewy bodies. The location of those clumps makes a difference.

  • When Lewy bodies are present in the brainstem, bodily functions that are controlled by the brainstem will be affected, causing symptoms such as constipation, depression and sleep disorders. Other important symptoms of Lewy body disorders include wide fluctuations in blood pressure, poor temperature control and bowel and bladder dysfunction.
  • When Lewy bodies affect the substantia nigra, located in the midbrain portion of the brainstem, hallmark motor symptoms will emerge including resting tremor, slowness and stiffness.
  • Lewy bodies can also affect areas beyond the brainstem, including the cortex or the ‘thinking part’ of the brain. When this occurs, cognitive symptoms become apparent. Patients may experience difficulty with executive function (planning, ordering, multi-tasking), visuo-spatial function (navigating, constructing) and memory. A variety of other symptoms can be prominent including visual hallucinations, fluctuating levels of alertness, apathy, agitation, anxiety, and delusions (believing something that isn’t true – e.g. that someone is stealing from the patient or that the patient is being watched by the CIA).

Symptoms of Parkinson’s Disease Dementia and Dementia with Lewy Bodies

In both PDD and DLB, symptoms caused by Lewy bodies in the lower brainstem (e.g. constipation, depression, sleep disorders), midbrain (e.g. resting tremor, slowness, stiffness) and cortex (e.g. cognitive difficulties, hallucinations,) can all occur.

Difference between Parkinson’s Disease Dementia and Dementia with Lewy Bodies?

Technically, the difference between these two conditions lies in how quickly the cognitive difficulties and hallucinations develop in relation to the movement issues. In DLB, the cognitive difficulties and hallucinations develop much sooner in the disease course than in PDD, sometimes even prior to the movement difficulties. Because of the similarities between PD, PDD, and DLB, current thinking in the medical community is that they should be viewed as related diseases which fall along a continuum of Lewy body disorders.

Treatments for Parkinson’s Disease Dementia and Dementia with Lewy Bodies

Treatments for DLB are similar to PDD and are aimed at symptom control. The motor symptoms of slowness, stiffness and walking difficulties can be treated with Levodopa. However, Levodopa can cause or exacerbate hallucinations, making it difficult to use it as a treatment for patients who have or are at risk of having hallucinations. Sometimes, clinicians will need to treat the hallucinations more aggressively in order for a patient to tolerate Levodopa given to help the motor symptoms. On the flipside, anti-psychotic medications to control hallucinations can worsen motor symptoms, so treating all the symptoms of LBD simultaneously can be a tricky balancing act.


Most of the available anti-psychotics are always avoided in both the DLB and PDD population because they block dopamine receptors and can cause significant motor dysfunction. However, two anti-psychotic medications, quetiapine and clozapine, are sometimes used in PDD and DLB patients as they have less of an ability to worsen motor symptoms. However, data for the use of quetiapine in these disorders is limited and clozapine requires the patient to undergo frequent blood draws to monitor blood counts. A newer medication pimavanserin, has a different mechanism of action, and does not block the dopamine system, but rather the serotonin system, and therefore does not increase motor symptoms.  It was approved by the FDA to treat PD psychosis, although the overlap between PDD and DLB may make it reasonable to try pimavanserin in DLB as well.

Medications for cognition

Cognitive symptoms in DLB can be treated with the same medications developed for other dementias. These include medications that such as donepezil and rivastigmine. Memantine is sometimes used as well.

DLB gained more visibility in the press when Robin Williams, the beloved comedian, died in 2014 with this condition. At APDA, we strive to further our understanding of Lewy body disorders through our research funding. Check out the research being done by our George C. Cotzias Fellowship awardee, Dr. Vivek Unni who is studying Lewy body formation and function. Very recently, Lewy body research conducted at University of Alabama, one of APDA’s Centers for Advanced Research was published. The study expanded our understanding of Lewy body formation in the memory part of the brain. For further reading on DLB, take a look at the latest consensus report of the DLB Consortium published in the journal Neurology.

Tips and take-aways

  • Focus less on the label that has been attached to your condition and seek to maximize both your physical as well as mental condition.
  • This means consulting with your physician to improve your medication regimen to treat all aspects of your disease – including motor symptoms, cognitive symptoms and hallucinations.
  • Always be open and honest with your doctor about all of the symptoms you may be experiencing so they can create the best treatment plan for you.
  • This also means that you must increase your level of physical, mental and social activities to keep your brain and body functioning at their best.

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