Insomnia In RLS Sufferers Linked To Brain Chemistry
May 9, 2013

Restless Legs Syndrome Linked To Glutamate Levels

Lee Rannals for - Your Universe Online

Researchers writing in the journal Neurology say they have found an explanation for the ties between sleepless nights and restless legs syndrome (RLS).

John Hopkins researchers used an MRI to snap images of the brain, and they found that a neurotransmitter involved in arousal known as glutamate is abnormally high in people suffering RLS. They saw that the more glutamate found in the brains of people with RLS, the worse they slept.

"We may have solved the mystery of why getting rid of patients' urge to move their legs doesn't improve their sleep," said Richard P. Allen, Ph.D., an associate professor of neurology at the Johns Hopkins University School of Medicine. "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."

During the study, the team conducted two-day sleep studies in the same individuals to measure how much rest each person was getting. The team used MRI images and recorded glutamate activity in the thalamus, which is the part of the brain involved with the regulation of consciousness, sleep and alertness. They looked at images of 28 people with RLS and 20 people without it. Patients with RLS in the study had symptoms six to seven nights a week persisting for at least six months.

Previous studies showed that even though RLS patients average less than 5.5 hours of sleep per night, they rarely reported problems with excessive daytime sleepiness. According to Allen, the lack of daytime sleepiness is likely related to the role of glutamate.

The researchers say their results may change the way RLS is treated, potentially helping patients suffering insomnia get a little more sleep at night. Currently, patients take dopamine-related drugs to help them sleep, but many of them eventually lose the benefit of the drug and require higher doses. Eventually, the medicine makes the symptoms even worse than before treatment.

"It's exciting to see something totally new in the field – something that really makes sense for the biology of arousal and sleep," Allen says.

Researchers just recently discovered that alcohol can actually trigger dopamine release in a person's brain, even without any effect from the alcohol it contains. The team writing in the journal Neuropsychopharmacology say the taste of an alcoholic drink alone can elicit dopamine activity in the brain.