Living brain study reveals unexpected lack of protein clumps during deep brain stimulation surgery

Mount Sinai researchers discovered that living people undergoing deep brain stimulation show a surprising absence of Lewy bodies in the prefrontal cortex, a finding that could lead to much more personalised care. The main takeaway from this major study is that the physical signs of Parkinson's in the brain do not always match up with how advanced someone's movement symptoms are. For a long time, scientists believed that as Parkinson's progressed, abnormal clumps of a protein called alpha-synuclein, known as Lewy bodies, would inevitably spread across the outer layers of the brain, including the prefrontal cortex. However, by looking at living brain tissue instead of waiting to study the brain after death, researchers found that this spread is simply not happening in everyone. This discovery matters because it completely changes our understanding of how the condition develops, which paves the way for changing care. By showing that clinical severity and the build-up of protein clumps can advance at completely different rates, the research proves that Parkinson's is not a one-size-fits-all condition. Instead, it suggests that there are distinct biological subtypes. People who qualify for deep brain stimulation might belong to a specific motor-predominant subtype, meaning their symptoms are heavily focused on movement issues while the outer layers of their brains remain largely unaffected by protein build-up. In the future, this insight will help doctors better predict how the condition will progress for different individuals and tailor therapies directly to a person's specific subtype rather than treating everyone the same way. It could also help identify exactly who will benefit the most from deep brain stimulation surgery. The investigation was made possible through Mount Sinai's Living Brain Project, a research initiative that allows scientists to study tiny tissue samples collected safely during necessary neurosurgical procedures like deep brain stimulation. Led by graduate student Ariela Buxbaum Grice, Assistant Professor Dr Noam Beckmann, neurosurgeon Dr Brian Kopell, and Professor Dr Alexander Charney, the team analysed prefrontal cortex biopsies from living people with Parkinson's and compared them to samples from people undergoing the same surgery for other neurological issues. The results were a total surprise to the medical community. Nearly every single biopsy from the people with Parkinson's was entirely negative for Lewy bodies. Furthermore, the vast majority also lacked Lewy neurites, which are the abnormal protein structures found in nerve cells associated with this pathology. Because these individuals had been living with advanced symptoms for many years, everyone expected to see a high burden of these protein clumps. To be absolutely certain of their findings, the scientists meticulously tested every possible laboratory or technical error that could explain the results. After confirming the near-absence was completely real, they compared the biopsies to matched tissues donated after death. The postmortem samples showed the expected high levels of widespread protein clumps, confirming that studying living tissue gives us a vastly different and more accurate picture of the condition during life. Ultimately, this research brings immense hope for better targeted treatments. By focusing on the biology of living individuals, scientists can move away from old assumptions and work toward personalised medicine that addresses the unique way the condition behaves in each person.