Restless leg syndrome (RLS) is a condition where
a person feels an irresistible urge to move the legs due to abnormal and
uncomfortable sensations in the legs
These sensations can interfere with sleep and result in insomnia.
Medications that are used to treat restless leg
syndrome currently do not significantly improve sleep. These medications increase the levels of
dopamine in the brain, which is a neurotransmitter implicated in the
development of restless leg syndrome.
Researchers now believe that another neurotransmitter
called glutamate may be associated with restless leg syndrome. Researchers from the Johns Hopkins
University School of Medicine found that glutamate levels in the brain
increased in people with restless leg syndrome. Glutamate is a neurotransmitter
that is involved in arousal. The levels
of glutamate were increased in a part of the brain called the thalamus, in
patients suffering from insomnia. The thalamus plays an important role in
regulation of sleep and alertness. This could possibly explain the sleeplessness
that these patients experience.
The researchers also suggest that the high
glutamate levels could explain the lack of excessive daytime sleepiness in
these individuals, despite suffering from reduced sleep duration at night.
Thus, targeting the excessive glutamate could
possibly help people with restless leg syndrome to get a good night's
Insomnia is the worst side effect of RLS. The
findings may change the way RLS is treated, according to the researchers.
"There are already drugs on the market, such as
the anticonvulsive gabapentin enacarbil, that can reduce glutamate levels in
the brain, but they have not been given as a first-line treatment for RLS
patients," says Richard Allen, associate professor of neurology at the
Johns Hopkins University School of Medicine and the lead investigator of the
"We may have solved the mystery of why getting rid
of patients' urge to move their legs doesn't improve their sleep,"
he continued. "We may have
been looking at the wrong thing all along, or we may find that both dopamine
and glutamate pathways play a role in RLS."
Further research is, however, required before glutamate antagonists can
be used for insomnia in restless leg syndrome patients.