The risk of developing Parkinson's is at least twice as high in people with anxiety compared to those without, finds a new study by UCL researchers.
The research, published in the British Journal of General Practice, investigated whether there was a link between people over the age of 50 who had recently developed anxiety and a later diagnosis of Parkinson's.
The team used UK primary care data between 2008 and 2018 and assessed 109,435 patients who had developed anxiety after the age of 50 and compared them to 878,256 matched controls who did not have anxiety.
They then tracked the presence of Parkinson's features - such as sleep problems, depression, tremor and balance impairment - from the point of their anxiety diagnosis up until one year before the date of a Parkinson's diagnosis, to help them understand each group's risk of developing Parkinson's over time and what their risk factors might be.
The team made sure to adjust the results to account for age, sex, social deprivation, lifestyle factors, severe mental illness, head trauma and dementia – which may affect the likelihood of developing the condition in people with anxiety.
Consequently, they found that the risk of developing Parkinson's increased two-fold in people with anxiety, compared to the control group.
They also confirmed that symptoms such as depression, sleep disturbance, fatigue, cognitive impairment, hypotension, tremor, rigidity, balance impairment, and constipation, were risk factors for developing Parkinson's in people with anxiety.
Co-lead author, Dr Juan Bazo Avarez (UCL Epidemiology & Health), said: "Parkinson's disease is the second most common neurodegenerative condition worldwide, and it is estimated that it will affect 14.2 million people by 2040.
"Anxiety is known to be a feature of the early stages of Parkinson's disease, but prior to our study, the prospective risk of Parkinson's in those over the age of 50 with new-onset anxiety was unknown.
"By understanding that anxiety and the mentioned features are linked to a higher risk of developing Parkinson's disease over the age of 50, we hope that we may be able to detect the condition earlier and help patients get the treatment they need."
Parkinson's disease is the world's fastest growing neurodegenerative disorder and currently affects nearly 10 million people across the globe.
The condition is a progressive disorder that is caused by the death of nerve cells in the part of the brain called the substantia nigra, which controls movement. These nerve cells die or become impaired, losing the ability to produce an important chemical called dopamine, due to the build-up of a protein called alpha-synuclein.
A team of researchers, led by scientists at UCL and University Medical Centre Goettingen, Germany, have recently developed a simple blood test that uses artificial intelligence to predict Parkinson's up to seven years before the onset of symptoms*.
Co-lead author Professor Anette Schrag (UCL Queen Square Institute of Neurology) said: "Anxiety is not as well researched as other early indicators of Parkinson's disease. Further research should explore how the early occurrence of anxiety relates to other early symptoms and to the underlying progression of Parkinson's in its early stages.
"This may lead to better treatment of the condition in its earliest stages."
The researchers advise that future research should explore why people aged over 50 with new-onset anxiety are more at risk of Parkinson's and whether their outcomes are affected by the severity of anxiety.
This study was funded by the European Union AND-PD grant.
* https://www.ucl.ac.uk/news/2024/jun/blood-test-could-predict-parkinsons-seven-years-symptoms
