Parasomnias Often Under-Recognized, Misunderstood
Research points way to new treatments for sleepwalking, sleep sex, and other parasomnias.
Acting Out Dreams continued...
Mahowald and Schenck have been studying a parasomnia that
strikes during a different stage of sleep -- REM (rapid eye movement) sleep,
when most dreaming occurs. What they found, Mahowald says, is a fascinating
link to neurological illnesses such as Parkinson's disease.
Normally during REM sleep, the muscles are completely
paralyzed, "so if you dream you are killing your mother-in-law, you're not
actually going to do it," Guilleminault says. But people with the
parasomnia dubbed REM sleep behavior disorder have an abnormality that causes
the normal paralysis of REM sleep to fail.
The result: Victims act out their dreams -- thrashing,
swearing, punching, kicking, running out of bed, even pummeling their bed
partners, Mahowald says.
Of the dozens of otherwise healthy people with REM sleep
behavior disorder that Mahowald and Schenk have followed since the 1980s,
two-thirds have gone on to develop Parkinson's disease or other related
neurodegenerative disorders, Mahowald says. Most are men, over 50 years old,
with the average time between the development of the sleep problem and the
neurological disorder being 13 years.
Taking the research a step further, other scientists have
implicated the same faulty brain chemistry in both disorders. In a recent study
of 13 people with the condition and 27 healthy individuals, Mayo Clinic
researchers found REM sleep behavior disorder is associated with low stores of
dopamine -- the same neurotransmitter known to be deficient in Parkinson
disease. The greater the loss of dopamine in the brain, the more severe the
symptoms, the researchers reported in the journal Neurology.
Other researchers have done brain imaging scans of people with
REM sleep behavior disorder. They found abnormalities in the region of the
midbrain where Parkinson's originates -- even in patients who did not yet have
signs of neurological problems.
Though the work is still early, it suggests that REM sleep
behavior disorder can be the first symptom of Parkinson's disease, Mahowald
says. "If we can develop a drug that protects against Parkinson's, this
will be very important."
Sleep Sex, Sleep Eating
Less well known and more recently recognized are sleep sex and
sleep eating disorder. "They have some characteristics of each of the other
[parasomnias], but don't quite fit the mold," Shapiro says.