Drugs that suppress immune system may protect against Parkinson's

May 31, 2018, Washington University School of Medicine
Immunohistochemistry for alpha-synuclein showing positive staining (brown) of an intraneural Lewy-body in the Substantia nigra in Parkinson's disease. Credit: Wikipedia

People who take drugs that suppress the immune system are less likely to develop Parkinson's disease, according to a study from Washington University School of Medicine in St. Louis.

The findings, published May 31 in Annals of Clinical and Translational Neurology, suggest that a person's own immune system helps nudge him or her down the path toward Parkinson's. Restraining the immune system with drugs potentially could prevent the neurological disorder, which is characterized by tremors, slow movements, stiffness and difficulty walking.

"The idea that a person's immune system could be contributing to neurologic damage has been suggested for quite some time," said Brad Racette, MD, the Robert Allan Finke Professor of Neurology and the study's senior author. "We've found that taking certain classes of immunosuppressant drugs reduces the risk of developing Parkinson's. One group of drugs in particular looks really promising and warrants further investigation to determine whether it can slow disease progression."

Parkinson's, a neurodegenerative disease, affects about a million people in the United States. Its causes are not well-understood.

Last year, Racette and colleagues analyzed millions of medical records and developed an algorithm to predict which people would be diagnosed with the disease. As they mined the data, they discovered that people with several types of , including ulcerative colitis, were less likely to be diagnosed with Parkinson's than the general population. The autoimmune diseases were a mixed bag, linked to myriad glitches in the immune system and affecting a variety of organ systems. It was hard to see how such a hodgepodge of immune system malfunctions all could end up having the same beneficial effect.

The researchers noted, however, that many autoimmune diseases do have one thing in common: They are treated with drugs that dampen immune activity. Having an autoimmune disease may not be a good thing, but being treated for one might be, they decided.

Racette and colleagues analyzed Medicare Part D prescription data on 48,295 people diagnosed with Parkinson's in 2009 and 52,324 people never diagnosed with Parkinson's. They identified 26 commonly prescribed immunosuppressant drugs, representing six classes of medications. The researchers determined which people in the data set had been prescribed any of the drugs a year or more before the date of diagnosis or by a pre-set cutoff date. Prescriptions written in the 12 months before diagnosis or by the cutoff were excluded to rule out any chance that the prescriptions might have been linked to early signs of the disease.

The researchers found that people taking drugs in either of two classes were significantly less likely to develop Parkinson's than those taking no immunosuppressants. People taking corticosteroids such as prednisone were 20 percent less likely to be diagnosed with Parkinson's, while those on inosine monophosphate dehydrogenase (IMDH) inhibitors were about one-third less likely.

When the researchers included specific autoimmune diseases in their analysis, the calculated risks didn't change, suggesting that the difference was due to use of the drugs, not the underlying diseases they were treating.

The findings suggest that tamping down immunity with drugs may keep Parkinson's disease at bay. But doing so also makes people more susceptible to infectious diseases and cancer. The benefits of immunosuppressive drugs outweigh the costs for people with serious autoimmune diseases like rheumatoid arthritis. But doctors probably would hesitate to prescribe risky drugs to healthy people to stave off Parkinson's, especially since there is no reliable way to predict who is on track to develop the disease.

"What we really need is a drug for people who are newly diagnosed, to prevent the disease from worsening," Racette said. "It's a reasonable assumption that if a drug reduces the risk of getting Parkinson's, it also will slow disease progression, and we're exploring that now."

Corticosteroids have many side effects, and doctors already try to minimize their use, so Racette and colleagues have turned their attention to IMDH inhibitors.

"Our next step is to conduct a proof-of-concept study with people newly diagnosed with Parkinson's disease to see whether these drugs have the effect on the immune system that we'd expect," Racette said. "It's too early to be thinking about clinical trials to see whether it modifies the , but the potential is intriguing."

Explore further: Medical history can point to earlier Parkinson's disease diagnosis

Related Stories

Medical history can point to earlier Parkinson's disease diagnosis

September 15, 2017
Before symptoms become pronounced, there is no reliable way to identify who is on track to develop Parkinson's disease, a debilitating movement disorder characterized by tremors, slowness of movement, stiffness, and difficulty ...

Link between IBD and Parkinson's might allow doctors to slow down condition

May 21, 2018
Doctors may be able to modify or slow down the progress of the neurological condition Parkinson's disease in the future by spotting signs of it in patients with inflammatory bowel disease (IBD), suggest a study published ...

A common anti-inflammatory therapy may help reduce risk of developing Parkinson's disease

April 23, 2018
A recent study from researchers at the Icahn School of Medicine at Mount Sinai provides new insights into a link between inflammatory bowel disease (IBD) and Parkinson's disease, and may have significant implications for ...

People with depression may be more likely to develop Parkinson's disease

May 20, 2015
People with depression may be more likely to develop Parkinson's disease, according to a large study published in the May 20, 2015, online issue of Neurology, the medical journal of the American Academy of Neurology.

Restless sleep may be an early sign of Parkinson's disease

December 6, 2017
Restless sleep could be a sign of a disorder associated with diseases of the brain. Researchers from Aarhus University conducted a case-control study on the condition of the dopamine-producing nerve cells in the brain and ...

Caffeine level in blood may help diagnose people with Parkinson's disease

January 3, 2018
Testing the level of caffeine in the blood may provide a simple way to aid the diagnosis of Parkinson's disease, according to a study published in the January 3, 2018, online issue of Neurology, the medical journal of the ...

Recommended for you

Study identifies chaperone protein implicated in Parkinson's disease

August 13, 2018
Reduced levels of a chaperone protein might have implications for the development and progression of neurodegenerative diseases such as Parkinson's disease and Lewy body dementia, according to new research from investigators ...

Function of gene mutations linked to neurological diseases identified

August 10, 2018
Several gene mutations have been linked to Parkinson's disease, but exactly how and where some of them cause their damage has been unclear. A new Yale study, published in the Journal of Cell Biology, shows that one of the ...

Biomarkers link fatigue in cancer, Parkinson's

August 9, 2018
Biological markers responsible for extreme exhaustion in patients with cancer have now been linked to fatigue in those with Parkinson's disease, according to new research from Rice University.

Researchers examining Parkinson's resilience

August 2, 2018
Diseases have a spectrum of risk, even those partially embedded in genes such as Parkinson's disease.

Japan human trial tests iPS cell treatment for Parkinson's

July 30, 2018
Japanese researchers on Monday announced the first human trial using a kind of stem cell to treat Parkinson's disease, building on earlier animal trials.

New ceria nanoparticles attack Parkinson's disease from three fronts

July 27, 2018
Researchers at the Center for Nanoparticle Research, within the Institute for Basic Science (IBS, South Korea), have developed a set of nanoparticles for Parkinson's disease treatment. Tested in mice and published in Angewandte ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Robin_Whittle
not rated yet May 31, 2018
On this basis one could argue that Parkinson's disease is to some significant extent an autoimmune disease.

It is a difficult argument to test through experiment, but it could also be argued that most or all diseases currently recognized as "autoimmune" exist solely or largely because in today's Western populations, few of us have helminths (intestinal worms) and most of us, I think, don't have H. pylori infections. Both these are known to systemically downmodulate some aspects of our immune system, and many researchers suggest that our current levels of immune system activity are higher than they should be, to the detriment of ourselves, due to the system evolving for hundreds of millenia in which our anscestors generally had lifelong helminth infestations, and I guess H. pylori infections as well.

Google "helminthic therapy" and "Trichuris suis therapy in Crohn's disease" for more on this.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.