Discovery of brain network that links body and mind could open the door to better Parkinson’s treatments

Two centuries after its discovery, Parkinson’s, the second most common neurodegenerative disease, still has neither a cure nor a known cause. The same is true for Alzheimer’s, the most common; and together they threaten an unprecedented health crisis because their incidence could double in the coming decades due to the aging population.

A study published on Wednesday could shed light on what happens inside the brain of a person with Parkinson’s disease and, in the future, help improve the effectiveness of current treatments. The findings were reported in the prestigious journal Nature.

In 1817, the British physician, geologist, and polemicist James Parkinson defined the condition after observing three of his patients and other affected individuals who walked with difficulty through the streets of London. It was later understood that, for reasons not entirely clear, neurons die in a region of the brain known as the substantia nigra — essential for producing dopamine and enabling bodily movement — and that this degeneration gives rise to the main symptoms: involuntary tremors, muscle rigidity, as well as depression, anxiety, insomnia, and a greater susceptibility to infections. Genetics accounts for only a portion of cases. The rest may stem from a complex interaction of factors, ranging from toxic agents such as pesticides to viral infections and problems in the gut–brain connection.

The new study identifies a brain network — the somato‑cognitive action network (SCAN), described in 2023 by the same team behind the work released this Wednesday — whose activity is characteristically altered in people with Parkinson’s. This network connects deep brain regions, such as the basal ganglia and the thalamus, with cortical areas involved not only in movement but also in attention, bodily perception, and action planning.

The researchers for the study, led by investigators from the United States and China, analyzed data from 863 patients with Parkinson’s disease and other neurological conditions such as essential tremor and amyotrophic lateral sclerosis, as well as healthy controls.

Through the analysis of resting-state functional magnetic resonance imaging, the authors observed that Parkinson’s patients exhibit abnormal hyperconnectivity between the SCAN network and dopamine-related cortical structures, a pattern that does not appear in other neurological disorders.

The study analyzed the effectiveness of the main treatments available, primarily the drug levodopa, as well as newer interventions such as deep brain stimulation, which requires implanting electrodes in the brain, and two non‑invasive techniques: transcranial magnetic stimulation and high‑intensity focused ultrasound, which selectively burn and deactivate areas of the brain involved in patients’ involuntary movements.

The results show that effective treatments reduce the hyperconnectivity of the SCAN network with the cerebral cortex. The physicians observed better outcomes when magnetic pulses and ultrasound were selectively directed at nodes of the SCAN brain network. Targeting these treatments to parts of this network could improve their effectiveness, the authors conclude.

These findings support a growing view of Parkinson’s as a disease that affects complex brain networks, which helps explain why many patients experience non‑motor symptoms — sleep disturbances, cognitive problems, fatigue — even before tremors or rigidity appear. In this way, Parkinson’s would not be only a movement‑related brain disease, but a disorder of the brain connections involved in thinking and planning as well as movement, especially the SCAN network.

“It’s an interesting and robust study that helps us understand how the brain malfunctions in these pathologies,” says Álvaro Sánchez Ferro, spokesperson for the Spanish Society of Neurology. “Although the conclusions aren’t groundbreaking, it’s true that until now, research had focused more on the brain nuclei where the neurons that generate movement, cognition, and emotions are located; and the neural networks that connect these centers had been somewhat neglected,” adds the neurologist from the 12 de Octubre Hospital in Madrid, who did not participate in the study.

For now, the work “has no direct application” to patients, cautions Sánchez Ferro. Before that, clinical trials will have to be conducted to confirm the results. Incorporating this type of analysis into routine clinical practice is also a challenge, as these types of neural networks are not routinely analyzed in hospitals, he adds. In any case, it is a step toward potentially improving the accuracy of certain non-invasive treatments. The study, the neurologist concludes, does not clarify the causes of the disease: “It’s like arriving at a crime scene. We see everything covered in blood, but we don’t know who the killer or killers are.”

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