Causes

The primary cause of restless legs syndrome is not known. Researchers are investigating neurologic problems that may arise either in the spinal cord or the brain. One current theory on the cause of restless legs syndrome involves a deficiency in a brain chemical called dopamine. RLS probably has a genetic basis in many cases, particularly those that develop before age 40. When the onset of the condition occur in older adults, it most likely due to some neurologic problem.

The central nervous system is comprised of the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.

Genetic Factors

People with restless legs syndrome often have a family history of the disorder. Researchers have begun to detect specific genetic locations or factors that might be responsible for this condition. Much of the research is based on studies of families with a strong history of RLS-related conditions. In 2005, researchers confirmed that a location on chromosome 12 is definitely linked to RLS. They named this genetic marker RLS1. Locations on chromosomes 14 and 9 may also be associated with hereditary forms of RLS.

Neurologic Abnormalities

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Dopamine and Neurologic Abnormalities in the Brain. Other research suggests that neurologic abnormalities involved with RLS and PLMD originate in the brain. A variety of studies support the hypothesis that an imbalance in neurotransmitters (chemical messengers in the brain), notably dopamine and serotonin, may play a part in RLS.Dopamine and serotonin unleash an array of nerve impulses that affect muscle movement. A similar effect is seen in Parkinson's disease, and indeed, drugs that increase dopamine are used for both disorders. (It should be noted that Parkinson's disease itself does not seem to increase the risk for RLS. Nor does RLS early in life predispose to Parkinson's later on. The two diseases then do not appear to share the same mechanisms.)