These are different but related neurological diseases that can cause issues with movement, thinking, and memory. No cure exists for either, but correct diagnosis and treatment can help to improve your quality of life.

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Lewy body dementia (LBD) and Parkinson’s disease (PD) are both disorders that impact someone’s ability to move and think. They have many similarities but also some important differences.

PD is a neurological disorder that affects motor movements. As the disease progresses, it may also impact the way a person thinks and their memory. Meanwhile, LBD is an umbrella term for two neurocognitive disorders that primarily affect memory and thinking. The disease may also impact a person’s movements.

Read on for more about how LBD is related to PD, including the differences and what treatments may help with both conditions.

Both PD and LBD share various characteristics.

For example, both are caused by protein deposits on the brain. These protein deposits consist of alpha-synuclein, which are called Lewy bodies. Both are chronic and progressive, meaning they tend to get worse over time. Both Parkinson’s disease and LBD affect some 1 million people in the United States, respectively. And both have no cure.


  • PD is caused by the death of nerve cells in a part of the brain that controls movement, the basal ganglia. It causes erratic and uncontrollable movements (tremors, shaking, etc.) and issues with coordination and balance. Over time, those affected may also develop dementia.
  • LBD is caused by protein deposits of alpha-synuclein (also called Lewy bodies) in the brain, and this affects cognition. It’s a type of dementia, a condition characterized by issues with thinking, language, and memory.

The key difference? PD is a movement disorder (it affects movements), and LBD is a cognitive disorder (it affects thinking).

Lewy body dementia or dementia with Lewy bodies?

The term “Lewy body dementia” is actually an umbrella term to cover 2 different types of dementia that can also be related to Parkinson’s disease. The first type is Parkinson’s disease dementia (PDD), and the second is dementia with Lewy bodies (DLB).

The greatest difference between the two types of dementia is the order in which symptoms arise:

  • With PDD, movement issues show up before dementia symptoms. Generally, if dementia occurs after 12 months of Parkinson’s, it’s considered PDD.
  • With DLB, symptoms of dementia show up first or within 12 months of Parkinson’s.
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PD and LBD are indeed linked.

Both are caused by a collection of proteins on the brain called Lewy bodies. When these proteins damage the brain, it results in issues with the brain’s production of neurotransmitters (dopamine and acetylcholine).

Researchers have found support for a genetic link between these conditions (as well as Alzheimer’s disease). Three gene links for these conditions were already known — GBA, APOE, and SNCA. An additional two genes — BIN1 and TMEM175 — were also discovered to be links.

One of the study authors explains, “[A]lthough Alzheimer’s and Parkinson’s disease are molecularly and clinically very different disorders, our results support the idea that the problems that cause those diseases may also happen in Lewy body dementia.”

If your issues started with tremors, shaking, or other uncontrollable movements, you may be experiencing PD. If your issues started with thinking or memory problems, you may be experiencing LBD.

Here’s a look at some of the classic symptoms of both:

Lewy body dementiaParkinson’s disease
fluctuations in thinking and memorymuscle stiffness
hallucinationsslow movement
sleeping issuesbalance and coordination issues
movement issues (simultaneous, later onset)cognitive issues (later onset)

The symptoms for the two Lewy body dementia types, PDD and DLB, may overlap as each progresses, making diagnosis difficult.

Doctors generally use a “1-year rule” to help with diagnosis:

  • With DLB, dementia symptoms should begin within 1 year of symptoms.
  • With PDD, dementia symptoms typically begin after the 1-year mark.

If you’re experiencing any of these symptoms, your best source for information is your doctor. Getting the right tests for proper diagnosis is important so you can receive the appropriate treatment for your condition.

Levodopa is a drug that helps with muscle movement, stiffness, and fluid motions (like walking, getting out of bed, etc.). It’s a first-line treatment for PD and is used in lower doses for LBD-related movement issues as well. The exception is in cases where people with LBD have hallucinations — it may worsen this symptom.

Other common medications for PD aren’t often used for people with LBD due to side effects. Likewise, deep brain stimulation is a surgical procedure that can help with PD-related movement issues. This procedure isn’t recommended for people with LBD, however, because it can worsen cognitive problems.

Regular exercise and physical therapy may help with the physical effects of both diseases.

Doctors may also recommend counseling to people with both conditions. Otherwise, treatment for LBD involves taking medications — donepezil, rivastigmine, clonazepam, and others — to improve a person’s symptoms as the diseases progress. Antipsychotic medications may also be used to treat more significant behavioral symptoms of LBD.

LBD and PD are different but related neurological diseases that can cause issues with movement, thinking, and memory. If you are having symptoms that concern you, make an appointment with your doctor.

While there’s no cure for either condition, correct diagnosis and treatment can help to improve your quality of life.