People with restless leg syndrome may be up to 60 per cent more likely to develop Parkinson’s disease, new research suggests.
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, usually at night, and an almost irresistible urge to move.
In severe cases, it can disturb sleep, harm mental health, and strain relationships and careers.
The researchers said: “Identifying risk factors for Parkinson’s disease and implementing early interventions are becoming increasingly important.
They added that it might be “more reasonable to interpret restless legs syndrome as a potential risk factor for developing Parkinson’s disease, rather than an early manifestation.”
Researchers from Korea University Ansan Hospital tracked 19,838 adults, half of whom had been diagnosed with restless leg syndrome, for an average of 15 years.
They found that 1.6 per cent of those with the condition developed Parkinson’s disease, compared with one per cent of those without it.
The study also found that people with restless leg syndrome who took dopamine agonists – medications such as pramipexole or ropinirole, which mimic dopamine activity in the brain – were less likely to develop Parkinson’s than those who did not take them.
Among those with restless leg syndrome, 0.5 per cent of patients taking dopamine agonists developed Parkinson’s, compared with 2.1 per cent not on medication.
Dopamine agonists are commonly prescribed to treat both Parkinson’s disease and moderate to severe restless leg syndrome, as dopamine plays a key role in controlling movement.
The researchers suggested the link between the two conditions may not be due to the dopamine pathway but another process, such as inflammation or changes in how the brain’s sensory systems work.
“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,” they 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.”
They cautioned that the findings should be interpreted carefully, as diagnoses were based on clinical assessment rather than laboratory testing, which may 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.
