Sleeping
disorders may be act as an early indicator of neurodegenerative diseases like
Parkinson's disease and Lewy body dementia (LBD) -- a type of dementia,
according to a study.
The
study focussed on patients with Rapid eye movement behaviour disorder -- a
sleep disorder where individuals physically act out their dreams during the
rapid eye movement (REM) stage of sleep.
"Normally,
when we're asleep and dreaming, our muscles are paralysed, but around age 50,
some people become very agitated during sleep and start punching, kicking and
screaming," said Shady Rahayel, a medical professor at Université de
Montréal in Canada.
Unlike
sleepwalking, which occurs during slow-wave sleep, RBD occurs during rapid eye
movement (REM) sleep, he added, and it affects people of middle age.
In
the study, published in the journal eBioMedicine, the researchers said that
nearly 90 per cent of people with the disorder will go on to develop either
Parkinson's disease or LBD.
“RBD
is an early warning sign that certain mechanisms in the brain are no longer
working as they should," said the team.
"The
people with RBD who come to see us are in good health... but of those who
subsequently develop a disease, half will have Parkinson's and the other half
LBD."
Rahayel
explained that with LBD, the second most common form of dementia after
Alzheimer's, "patients are no longer able to function in everyday
life".
In
addition to dementia, "they will have Parkinson's-like symptoms, vivid
visual hallucinations, fluctuating attention and other symptoms."
For
the study, the team used data from 1,276 MRI scans of people at risk of, or
with, Parkinson's disease or LBD, and also of healthy people.
Using
machine learning and computational models, the researchers identified two
trajectories of brain atrophy progression.
LBD
seems to be associated with brain atrophy that begins in the cortex and then
spreads to the interior of the brain, while in Parkinson's the atrophy
progresses from the interior to the exterior of the brain.
The
team next aims to investigate the factors that lead to this deterioration in
the cortex, such as vascular lesions, the effects of drugs, and of lifestyle
choices.
"Now
that we have identified these new progression patterns, our goal is to be able
to determine from an MRI whether a person has one of them so that we can
provide the best possible care," said Rahayel.
