In a seminal research paper, published in Lancet Neurology, researchers from King's College London have used brain scans to uncover early changes in the brain that may happen years before the symptoms of Parkinson's appear.
The study looked at serotonin signalling in the brains of people with extremely rare genetic mutations that meant they had a very high risk of developing Parkinson's in the future.
They showed that changes in serotonin signalling may happen in the earliest stages of Parkinson's - before significant loss of dopamine-producing cells. The changes could also be found ahead of dopamine cell loss in other areas of the brain, as the condition progressed.
Chemical messengers in Parkinson's
There are a number of neurotransmitters that the brain uses to communicate. Dopamine is most commonly associated with Parkinson's, with the condition causing the gradual loss of dopamine-producing cells.
But we now know that, while changes in dopamine account for many of the motor symptoms of Parkinson's, changes in other neurotransmitters like serotonin may play more of a role in symptoms such as sleep problems, fatigue and anxiety. And we know that some people with Parkinson's experience symptoms like these many months and even years before being diagnosed with the condition.
Research has previously shown associations between Parkinson's and serotonin, often thought of as the happy hormone, but this is the first study to show that changes in serotonin signalling may be an early consequence of Parkinson's, challenging the traditional view of what causes the condition.
Dr Beckie Port, Research Communications Manager, says:
"This is one of the first studies to suggest that changes in serotonin signalling may be an early consequence of Parkinson's.
"Detecting changes that are happening in the brain in these early stages is a crucial gap in Parkinson's research at the moment. Picking up on the condition earlier and being able to monitor its progression would aid the discovery of new and better treatments that could slow the loss of brain cells in Parkinson's.
"Further research is needed to fully understand the importance of this discovery, but if it is able to unlock a tool to measure and monitor how Parkinson’s develops, it could change countless lives."