A new study published in JAMA Network Open explored whether people with restless legs syndrome (RLS) are more likely to develop Parkinson’s disease (PD). The findings suggest that having RLS may increase your risk, but treatment could play a key role.
What is restless legs syndrome?
Restless legs syndrome is a neurological sleep disorder in which people have an urge to move their legs. Uncomfortable sensations can also be present, often described as crawling, creeping or itching. These sensations usually get worse in the evening or at night. People with RLS often have trouble falling asleep or staying asleep. Symptoms may ease temporarily when they move their legs, stretch or walk around.
The causes of RLS may vary from person to person. It could be related to low iron levels, diabetes, kidney failure, pregnancy or certain medications.
RLS may also be related to dysfunction in a part of the brain that controls movement. This part of the brain uses a chemical called dopamine to create smooth muscle movement. When dopamine levels are disrupted, this may result in involuntary movements.
The diagnosis of RLS is made by your physician based on the description of your symptoms. There is no blood, radiologic or sleep test necessary to make the diagnosis of RLS.
For people with severe symptoms, prescription medications can help. Some of the most common treatments affect the brain’s dopamine system, including medications such as pramipexole, ropinirole, rotigotine and levodopa. These dopamine agonists were once considered the gold standard for RLS, but a recently updated clinical practice guideline from the American Academy of Sleep Medicine now recommends against their routine use because of possible side effects and long-term complications. There are other prescription medications that can treat RLS that work on dopamine, gaba or opioid receptor systems.
Parkinson’s disease and dopamine
Parkinson’s disease is a progressive disorder of the nervous system that affects movement. It develops as nerve cells in the brain weaken and die, leading to tremors, stiffness, slow movement and balance problems. As the disease progresses, people may have difficulty walking, talking or completing everyday tasks.
In PD, the brain gradually loses dopamine, a chemical that helps control movement. Because both PD and RLS involve changes in dopamine, that may help explain why they cause similar movement problems and respond to some of the same treatments.
What the study found
Researchers in South Korea examined health data from nearly 20,000 people, including 9,919 with RLS and an equal number without. Both groups had an average age of 50 years, and about 63% were women.
Over time, PD developed in 1% of people without RLS and 1.6% of those with RLS. That means patients with RLS were more likely to develop PD than those without the sleep disorder.
The study also looked at how medication might influence that risk. People with RLS who were not treated with dopamine agonists were more likely to develop PD and tended to be diagnosed sooner. However, those who did take dopamine agonists were less likely to develop PD and were diagnosed later, suggesting that treatment may play a role.
Sleep disorders and Parkinson’s disease
Restless legs syndrome is not the only sleep disorder linked to Parkinson’s. REM sleep behavior disorder (RBD), a sleep disorder in which people physically act out their dreams, is also associated with a higher risk of developing PD later in life. In fact, RBD is sometimes seen as an early warning sign of Parkinson’s and other neurological diseases.
The takeaway
While RLS and PD are distinct neurological disorders, they share some similarities, including abnormal muscle movements and changes in brain activity that affect movement. Both are also linked to lower levels of dopamine.
Research suggests that RLS is more common in people with PD. One study found that about 16% of people with Parkinson’s also have RLS, compared with about 5% to 10% of the general population.
The new study adds to growing evidence that RLS may be connected to a higher risk of developing Parkinson’s later in life. However, studies on this topic have shown mixed results, partly because the way both conditions are diagnosed has changed over time.
Researchers are continuing to study what links the two and whether early recognition and care can help improve outcomes in the future. Both RLS and Parkinson’s can interfere with sleep, so if you are having ongoing sleep problems, talk with a sleep specialist or visit an accredited sleep center for help.
Medical review by: Shalini Paruthi, MD