Untreated restless legs syndrome may raise the risk of Parkinson’s disease, while dopamine-agonist therapy could lower it, a study has found.
Restless legs syndrome is a common neurological sleep disorder characterised by an uncontrollable urge to move the legs, often worsening at night.
Parkinson’s disease is a progressive condition that causes tremor, rigidity and slowed movement. Both are linked to problems in the brain’s dopamine system.
A joint research team analysed data from the Korean National Health Insurance Service Sample Cohort between 2002 and 2019.
The researchers identified 9,919 individuals with restless legs syndrome and compared them with an equal number of matched controls without the condition.
Over a median follow-up of 15 years, Parkinson’s disease developed in 1.6 per cent of patients with restless legs syndrome compared with 1.0 per cent of controls.
When analysed by treatment status, patients with untreated restless legs syndrome showed the highest incidence (2.1 per cent) and earlier onset, whereas patients treated with dopamine-agonist medication, which mimics the effects of dopamine in the brain, showed a lower incidence (0.5 per cent) and delayed onset compared with controls.
Jong Hun Kim, professor in the department of neurology at Korea University Ansan Hospital, who led the study, said: “These findings indicate the existence of ‘heterogeneity within RLS’ which allows for multiple interpretations.
“One of the interpretations is that restless legs syndrome may serve as an early clinical marker for Parkinson’s disease, particularly among untreated individuals.
“Our results also indicate that DA therapy, used for symptom control, may confer protective benefits to the brain’s motor pathways.”
The researchers propose that beyond dopamine dysfunction, other factors such as sleep disruption, iron deficiency, and immune or metabolic pathways may play a role in the association.
The protective trend observed with dopamine-agonist therapy could reflect neuroprotective mechanisms or improved identification of genuine restless legs syndrome cases that are distinct from early-stage Parkinson’s disease.
Kim added: “This dual pattern underscores the importance of recognising and managing restless legs syndrome early.
“Monitoring and treating RLS may not only improve sleep quality but could also influence long-term neurological health.”
