People who suffer from agonising restless leg syndrome may be at greater risk of developing Parkinson’s disease, concerning research has suggested.
The condition, which affects up to 10 per cent of the population and is more common in women, causes an unpleasant ‘crawling’ sensation in the legs, mostly at night, and an almost irresistible urge to move.
In those worst affected, it can interrupt sleep, damage mental health, ruin relationships and careers.
But now, Korean researchers have discovered those with the condition were up to 60 per cent more likely to develop the progressive neurological illness, Parkinson’s.
The scientists, who tracked almost 20,000 adults, also found that those with restless leg syndrome who took dopamine agonists—medication such as pramipexole or ropinirole, which mimic dopamine activity in the brain—were less likely to develop Parkinson’s than those who didn’t.
Experts today suggested the findings showed restless leg syndrome may be a ‘potential risk factor for Parkinson’s’.
Further research, however, was vital to prove exactly what caused this increased risk.
Writing in the journal JAMA Network Open, they said: ‘Identifying risk factors for Parkinson’s disease and implementing early interventions are becoming increasingly important.
It may be ‘more reasonable to interpret restless legs syndrome as a potential risk factor for developing Parkinson’s disease, rather than an early manifestation,’ they added.
Parkinson’s disease occurs when brain cells called dopaminergic neurons progressively break down, leading to a deficiency of dopamine.
This dopamine deficit impairs communication between brain cells, causing the symptoms of Parkinson’s disease, such as tremors, slowed movement, and balance problems, because dopamine is essential for fine-tuning muscle control.
In the study, the scientists from Korea University Ansan Hospital, tracked 19,838 patients, half of which had been diagnosed with restless legs syndrome.
Over a follow-up of 15 years on average, 1.6 per cent of those with the syndrome developed Parkinson’s, compared to just one per cent without.
Among those with restless leg syndrome, 0.5 per cent of patients taking dopamine agonists developed Parkinson’s.
By contrast, 2.1 per cent of those not on medication were diagnosed with the condition.
Dopamine agonists are commonly prescribed not only for Parkinson’s disease but also for moderate to severe restless legs syndrome, because dopamine is thought to play a role in both conditions.
Symptoms can include uncontrollable tremors, slow movements and muscle stiffness, but experts say they often only appear when about 80 per cent of the nerve cells have been lost
‘The dopamine agonist-treated group tended to be at decreased risk of developing Parkinson’s disease, whereas the dopamine agonist-nontreated group tended to be at increased risk,’ the researchers said.
‘This suggests that the association between restless legs syndrome and Parkinson’s disease might not be due to the dopaminergic pathway, but rather a different mechanism.’
Instead, it could involve another underlying process—such as inflammation or changes in how the brain’s sensory systems work—that increases the risk of both, they suggested.
However, it was vital further research was done to prove the findings, they added.
They also cautioned that the findings should be interpreted carefully, as the diagnoses were based on clinical judgement rather than laboratory tests, which could have led to some cases being missed or misclassified.
‘For example, rapid eye movement sleep behaviour disorder, a well-known early feature of Parkinson’s disease, may have been misdiagnosed as restless legs syndrome in some cases,’ they wrote.
In the UK around 166,000 people are living with Parkinson’s, a figure that is worryingly expected to double by 2050.
While not directly fatal, the disease leaves sufferers more vulnerable to life-threatening infections.
Back to the Future film star, Michael J Fox, was diagnosed with Parkinson’s at just 29, in 1991
Famous figures who have battled the disease include actor Michael J. Fox, who was diagnosed in 1991 at just 29, and went public seven years later.
Since then, the Back to the Future star has become the leading campaigner for research, founding The Michael J. Fox Foundation, which has raised billions to find a cure.
Rock legend Ozzy Osbourne revealed in 2020 that he had been diagnosed the year before, describing the toll it has taken on both his body and mind.
The Black Sabbath frontman, who died in July, spoke candidly about the ‘never-ending’ struggle with the disease and how it has forced him to scale back performing.
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