Causes of Restless Legs Syndrome
Often there is no known cause for restless legs syndrome (RLS).
Heredity
RLS runs in families especially if the RLS begins before the age of 40. Researchers have identified a number of chromosomes that are associated with RLS. Genetics plays a massive role; 40% to 90% of individuals with RLS have at least one first-degree relative with the condition.
Age
RLS can occur at any age even in children. Approximately 2% to 4% of children and adolescents are affected by RLS. However, RLS is more likely to occur as age increases. Most people are diagnosed after age 40.
Gender
RLS is approximately twice as common in women. Higher RLS prevalence in women is often attributed to pregnancy. About 1 in 4 pregnant women experience RLS, particularly during the third trimester. The good news is that it normally subsides after delivery. Other factors leading to RLS in women include iron deficiency (due to menstruation) and hormonal fluctuations.
Dopamine
Researchers have identified that in people with RLS there is an imbalance in dopamine in the brain. Dopamine is involved in the transmission of messages controlling muscle movement. Likely due to the circadian rhythm RLS symptoms tend to worsen at night due to low dopamine. This is often exacerbated by low brain iron levels, which are necessary for dopamine production. It is not always a lack of dopamine, but rather a complex dysfunction in dopamine receptors (D2R) that causes the neurological urge to move.
Iron
The relationship between low iron and RLS is one of the most critical factors in understanding the condition. Iron is a fundamental requirement for brain chemistry that regulates movement.
Iron is a necessary "cofactor" for an enzyme called tyrosine hydroxylase. This enzyme is responsible for producing dopamine in the brain. So low iron leads to low tyrosine hydroxylase such that the result is a reduced amount of dopamine in turn leading to RLS. Since dopamine is the neurotransmitter that controls smooth, purposeful muscle movement, a lack of it leads to the "misfiring" signals yielding the crawling, tingling, and irresistible urge to move characterizing RLS.
Go to your medical physician and have an iron studies blood test. For the general population, a ferritin level of 30 ng/mL might be considered "normal." However, for someone with RLS, medical guidelines often suggest keeping ferritin levels above 75 ng/mL or even 100 ng/mL to manage symptoms.
Peripheral neuropathy
Peripheral neuropathy is a condition whereby there is damage to the nerves in the hands and or feet. People with peripheral neuropathy are more likely to develop RLS.
Parkinson's disease
Parkinson’s disease is a neurological disorder that elicits a drop in dopamine in the brain region substantia nigra die effecting movement, balance and coordination. People with Parkinsons are more likely to develop RLS.
Medications
Some medications for other disorders may lead to RLS. These include some antidepressants, antipsychotic, antinausea, cold and allergy medications. These are further discussed in the page “Medications affecting restless legs syndrome”.