Researchers at Washington university school of medicine in St. Louis identified the earliest signs of Parkinson's disease in the brain before patients developed Parkinson-related symptoms. The findings, published in the journal Cell, suggest a new view of the disease and could lead to the development of screening tools to identify the most at risk.

Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's. The disease is characterized by motor and cognitive problems that start in the brain long before a patient is diagnosed. The early stages of Parkinson's disease are critical, and treating it as early as possible may slow its progress.

The new study is the first to demonstrate the key role of the brain chemical serotonin in the early stages of Parkinson's disease. The results suggest that systemic changes in serotonin may be an important warning sign of the disease.

The researchers said: "traditionally, Parkinson's disease is caused by damage to the dopamine system, but we found that changes in the serotonin system occur first, before patients begin to show symptoms. "The results suggest that early changes in the serotonin system could provide insights into new treatments that could slow the progression of Parkinson's disease and ultimately stop it."

α-Synaptic nuclein (SNCA) is present in the brain of Parkinson's disease patients. People with mutations in theα-Synuclein gene are extremely rare, but they are almost certain to develop Parkinson's disease, making them a prime candidate for Parkinson's research. The researchers compared 20 patients with a mutation in the synaptic nuclein gene with 20 healthy volunteers and found that the serotonin system in Parkinson's patients began to malfunction before symptoms that affect movement began.

Lead author Heather Wilson said: "we found that serotonin function is an important marker for the development of Parkinson's disease. And we found detectable changes in the serotonin system in undiagnosed patients. Therefore, brain imaging of the serotonin system can be an important tool in detecting the risk of Parkinson's disease, monitoring its progress and helping to develop new treatments."