Once you start to suffer from Parkinson’s motor symptoms, you may have had the condition for as long as 10 years or more, a new study by the Université of Montréal (UdeM) in Canada suggests.
A team led by UdeM neuroscientist Louis-Éric Trudeau showed that the brain is surprisingly resilient during the asymptomatic period of Parkinson’s, before diagnosis.
Parkinson’s is a disease of the central nervous system caused by the loss of dopamine-producing cells in the brain.
In a UdeM study on mice, Trudeau and his researchers used genetic manipulations to stop neurons from releasing dopamine. As dopamine is important for movement, it was expected that the mice would lose motor function as a result. Instead, the study found that movement circuits in the brains of mice were unaffected despite an almost total loss of active secretion of dopamine.
“This observation went against our initial hypothesis, but that’s often the way it is in science, and it forced us to re-evaluate our certainties about what dopamine really does in the brain,” said Trudeau, a professor in UdeM’s Department of Pharmacology and Physiology and Department of Neurosciences.
Meanwhile, measurements of overall dopamine levels in the brains of the mice were found to be normal.
These results suggest that the activity of movement circuits in the brain requires only low basal levels of dopamine.
The team believe it is therefore likely that in the early stages of Parkinson’s, basal dopamine levels in the brain remain sufficiently high for many years despite the gradual loss of dopamine-producing neurons. It is only when a minimum threshold is exceeded that motor changes appear.
Read the full study published in Nature Communications.
