Certain immune activity could be increasing a person’s risk of developing Parkinson’s disease (PD), but immunosuppressant drugs might solve the problem. In a new study from the Washington University School of Medicine, researchers show how they inadvertently discovered the role of immunosuppressant drugs in PD development.
"The idea that a person's immune system could be contributing to neurologic damage has been suggested for quite some time," explained senior author Brad Racette, MD. "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."
Racette and others used data from millions of medical records to design an algorithm for predicting the people who will develop PD. From analyzing the algorithm and its predictions, researchers found that people with autoimmune diseases were less likely to develop PD. However, this relationship wasn’t from a direct link between autoimmune pathology and PD. Rather, the immunosuppressant drugs prescribed to virtually all people with autoimmune disease appeared to be the significant factor.
Immunosuppressant drugs are prescribed to people with autoimmune disease to treat various symptoms. These drugs dampen the immune system, reducing the symptoms that arise when the immune system mistakenly attacks the body’s own tissues, the key characteristic of autoimmunity.
Moving forward with their first clue, the researchers then analyzed drug data from 48,295 people diagnosed with PD and 53,324 people not diagnosed with PD. Of 26 commonly prescribed immunosuppressant drugs from six classes of medications, two classes were linked to a significant decrease in PD risk, compared to people taking no immunosuppressant drugs.
Specifically, corticosteroids lowered the risk of PD by 20 percent, and inosine monophosphate dehydrogenase (IMDH) drugs lowered the risk of PD by one-third.
However, researchers also need to consider the ever-present danger of suppressing the immune system, whether to treat autoimmune disorders or for some other reason, like reducing the risk of PD.
"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."
Parkinson’s disease is a disorder characterized by progressive degeneration of the dopamine-producing neurons of the substantia nigra, the area of the brain responsible for movement and coordination. Symptoms occurring as a result of PD include tremors, limb rigidity, and gait and balance problems.
The main cause of PD is still unknown, and there is no cure. Treatment options are available, including drugs and surgical options. About one million people are impacted by PD in the United States alone.
The present study was published in the journal Annals of Clinical and Translational Neurology.