Australian researchers have developed a way of highlighting changes in the brain that mark the progression of Parkinson’s disease years before physical symptoms show.
Researchers at the Florey Institute and Austin Health in Melbourne have shown it is possible to detect signs of Parkinson’s disease, a debilitating neurodegenerative condition, by injecting patients with a synthetic compound, known as 18F-AV-133, designed to bind to a protein in the brain known as VMAT2.
There is significant evidence that deficiency of VMAT2, an essential protein for neurotransmitter regulation, is linked to Parkinson’s disease.
The F-AV-133 compound becomes concentrated in areas of the brain where VMAT2 is active, with researchers then able to conduct a PET scan to capture images that show the strength and areas of VMAT2 activity in the brain, creating an imaging biomarker.
The researchers studied 26 patients with Parkinson’s disease, a control group of 12 people, and 11 people with Rapid Eye Movement (REM) sleep behaviour disorder, which is a significant indicator of Parkinson’s disease. Each person undertook two PET scans two years apart.
The were no significant changes in clinical symptoms in any of the participants according to currently available assessments for Parkinson’s disease, which involve asking people questions about their symptoms.
By contrast, the PET scans showed significant neuronal loss in three key regions of the brain in individuals with Parkinson’s disease, and in one key area of the brain in those with REM disorder, suggesting F-AV-133 is a more sensitive means of monitoring neurodegeneration.
The findings were published in the international journal Neurology on Thursday.
The study’s lead researcher, Prof Kevin Barnham, said Parkinson’s disease is often thought of as an illness of old age, when in fact it starts in midlife and can go undetected for decades.
“Parkinson’s disease is very hard to diagnose until symptoms are obvious, by which time, up to 85% of the brain’s neurons that control motor coordination have been destroyed,” he said.
“At that point, many treatments are likely to be ineffective. Our long-term goal is to find a way to detect the disease much earlier and treat people before the damage is done.”
He said further mathematical modelling conducted on the study data had found the imaging biomarker may be able to detect Parkinson’s disease up to 30 years before symptoms appear.
Degeneration happens in the brains of people with Parkinson’s before clinical diagnosis.
This is because there needs to be comprehensive loss of nerve cells that produce a chemical called dopamine before physical symptoms show, said Assoc Prof Lyndsey Collins-Praino, a neurodegenerative diseases expert and senior lecturer in medicine with the University of Adelaide.
“So in recent years, there’s been a big push in the field to try to identify what are called the prodromal symptoms of Parkinson’s, which are early warning signs and include things like reduction in the sense of smell, constipation, anxiety, and REM sleep behaviour disorder which is the most predictive indicator,” she said.
She said the Parkinson’s field lags behind Alzheimer’s, which has much more extensively incorporated the use of biomarkers in research and testing. This is despite Parkinson’s being the fastest-growing neurological disease.
“In Parkinson’s, diagnosis is almost entirely based on subjective clinical judgment and to move forward, the field really does need to incorporate biomarkers,” Collins-Praino said.
Information for people living with Parkinson’s can be found at Fight Parkinson’s, or by phoning 03 8809 0400
