Can GLP-1 Agonists Help With Parkinson’s Disease?

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A potential new treatment for Parkinson’s comes up short but offers a glimmer of hope for younger patients.

A new trial investigating whether GLP-1 agonists, more popularly known under their brand names Ozempic and Victoza, offered hints that these injectable medications might help relieve tremors and other movement problems in younger participants.

The Study May Have Been Too Short

The research team hypothesized that GLP-1 agonists could help reduce neuroinflammation in the brains of individuals with early-stage Parkinson’s disease. This inflammation is caused when microglia, specialized immune cells that support neurons, become overactivated and dysfunctional. Since the brain has receptors for GLP-1 and the medication has anti-inflammatory effects, the scientists theorized it might help calm the microglial response.

In the randomized placebo-controlled study, which took place over the course of nearly three years, 255 participants received either a placebo or one of two doses—2.5 mg or 5 mg—of the GLP-1 drug NYL01. Each group contained around 85 participants. On average, volunteers were 61.5 years old and over half were male.

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Results showed no significant differences between the NYL01 treatment groups and the placebo group in terms of two key outcomes - Parkinson’s disease motor symptoms (tremors, rigidity, impaired movement) or non-motor features (brain fog, depression, insomnia).

However, the research team found reduced motor symptoms in participants under age 60 compared to individuals receiving the placebo. They hypothesize this subgroup benefit owes to more rapid decline in the placebo group.

The lack of efficacy in the full study group may stem from its short duration. Another trial currently underway is assessing the GLP-1 drug exenatide over two years in 200 Parkinson’s patients, with results expected in 2024. The longer time period could better reveal any protective effects of GLP-1 agonists for slowing Parkinson’s progression.

The Complex Link Between Diabetes and Parkinson’s

It’s no coincidence that a diabetes medication was tested in Parkinson’s disease research. Physicians and researchers have known for a long time that the two conditions share a close relationship. According to the United Kingdom’s Cure Parkinson’s organization, “a significant proportion of people with Parkinson’s have glucose intolerance and some also live with the added burden of diabetes.”

In fact, some research shows people with diabetes have roughly 40 percent higher risk of developing Parkinson’s compared to the general population. And those with both conditions often see faster progression of Parkinson’s symptoms.

What do they have in common?

What connects the two diseases is likely insulin, according to some research. In the brain, insulin regulates glucose levels. It also impacts levels of dopamine, which enables communication between nerve cells. Insulin further influences cognitive functions like clear thinking, learning, and memory—all affected in Parkinson’s. Dysfunction in the brain’s insulin processing could thus contribute to Parkinson’s disease.

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It is important to note that not every patient with diabetes develops Parkinson’s or vice versa. However, certain additional risk factors can compound susceptibility. These include age at diabetes diagnosis and diabetes complications. Studies show earlier-onset diabetes heightens future Parkinson’s risk. Likewise, more diabetic complications correlate to higher Parkinson’s risk.

Another Common Diabetes Drug May Slow Progression

Exenatide is being used experimentally to treat Parkinson’s disease patients with diabetes in the United Kingdom, following promising results from multiple studies.

In a 2008 trial with 45 participants, half received exenatide injections twice daily while half received a placebo. Those given exenatide did not experience the movement decline typically seen in Parkinson’s patients.

Another 2017 large phase 2 clinical trial found exenatide likely slows Parkinson’s progression, particularly motor symptoms like tremors and stiffness.