A newly identified brain network may be the real driver of Parkinson'sÄand precisely targeting it just delivered a major boost in symptom relief.

Parkinson's disease is a progressive neurological condition that affects more than 1 million people in the United States and over 10 million worldwide. It causes a wide range of disabling symptoms, including tremors, difficulty with movement, sleep problems, and declines in thinking and memory. Existing treatments such as long-term drug therapy and invasive deep brain stimulation (DBS) can ease symptoms, but they do not stop the disease from worsening or provide a cure.



A New Brain Network Linked to Parkinson's

An international research team led by China's Changping Laboratory, working with Washington University School of Medicine in St. Louis and other institutions, has identified a specific brain region tied to the central problems of Parkinson's disease. The scientists focused on a brain network known as the somato-cognitive action network (SCAN). When this network was targeted using a non-invasive experimental approach called transcranial magnetic stimulation (TMS), patients experienced more than twice the symptom improvement seen when nearby brain regions were stimulated instead.

The findings, published today (February 4) in Nature, reshape how scientists understand the neurological basis of Parkinson's disease and point toward
more precise and potentially more effective treatment strategies.

"This work demonstrates that Parkinson's is a SCAN disorder, and the data strongly suggest that if you target the SCAN in a personalized, precise manner you can treat Parkinson's more successfully than was previously possible,"
said co-author Nico U. Dosenbach, MD, PhD, the David M. & Tracy S. Holtzman Professor of Neurology at WashU Medicine. "Changing the activity within SCAN could slow or reverse the progression of the disease, not just treat the symptoms."

SCAN Parkinson's Healthy Brain

The brain network that links thinking with movement, called SCAN, was first described by WashU Medicine researchers in 2023 and has been identified in a new study as the neurological basis of Parkinson's disease. An experimental therapy that targeted this network more than doubled symptom improvement in a small group of patients with Parkinson's, which is characterized by hyperconnectivity (left side of illustration) between SCAN and the brain's subcortex. Credit: Sara Moser/WashU Medicine


Understanding the Role of SCAN

Dosenbach first described the SCAN in Nature in 2023. This network sits within the motor cortex, the area of the brain that controls voluntary movement, and helps translate plans for action into physical motion while monitoring how those actions unfold. Because Parkinson's disease affects far more than movement alone, influencing digestion, sleep, motivation, and cognition, senior author Hesheng Liu, PhD, partnered with Dosenbach to investigate whether problems within SCAN could explain the disease's wide-ranging symptoms and offer a new treatment target.

To explore this idea, Liu's team analyzed multiple types of brain imaging
data from more than 800 participants in the United States and China. The study included people with Parkinson's disease receiving DBS or non-invasive therapies such as transcranial magnetic stimulation, focused ultrasound stimulation, and medications. Healthy volunteers and individuals with other movement disorders were also included for comparison.



Abnormal Brain Connectivity Identified

The researchers found that Parkinson's disease is marked by unusually strong connections between the SCAN and the subcortex, a brain region involved in emotion, memory, and motor control. Across all four treatments examined in the study, the therapies worked best when they reduced this excessive connectivity. Doing so helped restore more normal activity in the brain circuit responsible for planning and coordinating actions.

"For decades, Parkinson's has been primarily associated with motor deficits
and the basal ganglia," the part of the brain that controls muscle movements, Liu said. "Our work shows that the disease is rooted in a much broader
network dysfunction. The SCAN is hyperconnected to key regions associated with Parkinson's disease, and this abnormal wiring disrupts not only movement but also related cognitive and bodily functions."

Precision Treatment Shows Promise

Using these insights, the researchers developed a precision treatment system designed to target the SCAN without surgery and with millimeter-level accuracy. They used transcranial magnetic stimulation, which delivers magnetic pulses to the brain through a device placed on the scalp. In a clinical trial, 18 patients who received SCAN-targeted stimulation showed a 56% response rate after two weeks. By comparison, only 22% of 18 patients who received stimulation to nearby brain areas improved, representing a 2.5-fold increase in effectiveness.

"With non-invasive treatments, we could start treating with neuromodulation much earlier than is currently done with DBS" because they don't require
brain surgery, Dosenbach said.

He noted that additional basic research is still needed to determine how different parts of the SCAN contribute to specific Parkinson's symptoms.

Looking ahead, Dosenbach plans to lead clinical trials with Turing Medical, a WashU Medicine startup he co-founded. These studies will test a non-invasive therapy that uses surface electrode strips placed over SCAN regions to improve walking difficulties in people with Parkinson's disease. He also intends to explore low-intensity focused ultrasound as another non-invasive method for adjusting SCAN activity using acoustic energy.


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