Parkinson's may be detectable 20-30 years before clinical diagnosis: Study

Signs of Parkinson's disease could potentially be identified 20-30 years before symptoms appear, Australian researchers have said.

Utilising a biomarker named F-AV-133 in combination with PET (positron emission tomography) scans enables the diagnosis of Parkinson's disease and precise monitoring of neurodegeneration, researchers from the Florey Institute of Neuroscience and Mental Health in Melbourne said.

F-AV-133 is an imaging agent and has shown promise as a PET tracer for detecting and monitoring neurodegeneration in Parkinson's disease, a progressive neurological disorder characterised by tremors and impaired muscular coordination.

According to the researchers, the disease, often thought of as an illness of old age, in fact, 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 per cent of the brain's neurons that control motor coordination have been destroyed. At that point, many treatments are likely to be ineffective," said Kevin Barnham, professor at The Florey and lead researcher of the study published in the journal Neurology.

In their study, 26 patients already diagnosed to have Parkinson's disease and a control group of 12 people were scanned, along with 11 other people having Rapid Eye Movement sleep behaviour disorder (RBD), a strong indicator of the disease. All of them undertook two PET scans two years apart.

The researchers found that the PET scans showed a significant loss in the nerve cells or neurons in three key regions of the brain in individuals with the disease, even as no significant changes in their clinical symptoms were seen according to currently available diagnostic assessments.

The findings suggest that F-AV-133 is a more sensitive means of monitoring neurodegeneration than what is now available, the researchers said in their study.

Using mathematical modelling, they found that when clinical symptoms of the disease begin to show and are sufficient for diagnosis, approximately 33 years' worth of slow neuronal loss has already taken place.

However, only about 10.5 years' worth of this neuronal loss happens before the disease can be detected on a PET scan, they said. Thus, they say that this diagnostic technique could help detect Parkinson's disease more than 20 years sooner than clinical diagnosis.

RBD is a significant warning sign for early Parkinson's disease and people having RBD are known to often shout or thrash around, sometimes violently, in their sleep while acting out vivid and unpleasant dreams.

About half of people with Parkinson's have RBD and roughly 90 per cent of people with RBD are likely to develop a parkinsonian condition. If one has RBD, it is suggested that they consult with a sleep specialist or a neurologist.

(PTI)