People with Parkinson’s disease have abnormal numbers of Lewy bodies. These proteins in nerve cells may contribute to the development and progression of Parkinson’s.

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Parkinson’s disease (PD) is a neurological condition that mainly affects movement. According to the Parkinson’s Foundation, almost 1 million people in the United States are living with PD.

In people with PD, nerve cells important for movement are damaged and begin to die. Abnormal accumulations of a protein called Lewy bodies are believed to contribute to this.

Lewy bodies are abnormal accumulations of protein that occur in nerve cells in the brain. They were first described in 1912 in the brains of people with PD.

Lewy bodies are spherical. While some nerve cells may only have one Lewy body, it’s also possible for nerve cells to have multiple Lewy bodies.

The major component in Lewy bodies is the protein alpha-synuclein. This protein is believed to be important for communication between nerve cells.

In PD and other conditions associated with Lewy bodies, alpha-synuclein has an abnormal structure that promotes its accumulation. This eventually leads to the formation of Lewy bodies within affected nerve cells.

While the exact cause of PD is not yet fully understood, Lewy bodies are believed to contribute in some way. Indeed, some people with PD have mutations in the gene that encodes alpha-synuclein, called SNCA.

According to the National Library of Medicine, at least 30 mutations associated with PD have been found in the SNCA gene. These can lead to changes in the structure of alpha-synuclein or to excess production of the protein within cells.

However, most instances of PD cannot be traced to a known gene mutation. This means that other things, such as unknown genetic factors and environmental factors, contribute to PD as well.

Regardless, once Lewy bodies are present, it’s still unclear how exactly they lead to the damage or death of nerve cells. However, scientists do have some ideas.

For example, a 2019 study found that Lewy bodies also contain other cellular factors in addition to alpha-synuclein. This led to crowding within the affected cells, potentially disrupting the movement of various components within the cell.

Additionally, a 2020 study found that the steps leading to Lewy body formation disrupt several important processes in nerve cells. As such, researchers state that the Lewy body formation process is what may drive the nerve cell damage associated with PD.

What is Lewy body dementia?

Lewy body dementia is dementia associated with Lewy bodies in the brain. According to the National Institute on Aging, it’s one of the most common causes of dementia, affecting over 1 million people in the United States.

Clinically, Lewy body dementia is a form of dementia characterized by fluctuating cognition and alertness, visual hallucinations, and features of parkinsonism.

Like PD, what exactly causes Lewy body dementia isn’t known. It’s possible that the Lewy bodies may contribute to the loss of nerve cells important for functions like memory, thinking, and movement.

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While all people with PD have Lewy bodies, they’re not an important part of a PD diagnosis. This is because the presence of Lewy bodies can only be confirmed by analyzing brain tissue after death.

Instead, the diagnosis of PD involves a careful physical and neurological evaluation. Laboratory tests and brain imaging can be helpful in ruling out other conditions that cause similar symptoms to PD.

It’s unclear what exactly puts a person at risk of Lewy bodies in general. However, some known risk factors for PD include:

  • being an older age
  • being assigned male at birth
  • having other close family members with PD
  • having a history of exposure to certain pesticides

PD is a progressive condition. This means its symptoms continue to slowly worsen as time passes. Because every person with PD is different, it’s hard to be able to predict how PD will progress among different people.

People with PD are also at risk of developing PD dementia. PD dementia is a type of Lewy body dementia.

In PD dementia, significant declines in thinking and memory happen after a person has been living with the motor symptoms of PD. Up to 70% of people with PD develop dementia as their PD progresses, notes the Parkinson’s Foundation.

Can the formation of Lewy bodies be prevented?

Not at this time. Since we don’t know what exactly causes Lewy bodies to form in the first place, there’s currently no known way to prevent them.

Can you have Lewy bodies and not know it?

Yes. Older research estimates that 8% to 17% of people over age 60 with typical neurological function have Lewy bodies. This is called incidental Lewy body disease. It may be a precursor to PD or Lewy body dementia.

Lewy bodies are abnormal accumulations of protein that happen in the nerve cells of people with PD. Their main component is a protein called alpha-synuclein.

It’s unknown how exactly Lewy bodies contribute to PD. Generally speaking, it’s likely that they disrupt the typical functioning of nerve cells, eventually leading to their death.

There’s currently no cure for PD. However, treatments can help manage its symptoms.