Neuroimaging can predict which patients with rapid-eye-movement sleep behaviour disorder (IRBD)* are at the greatest risk of developing neurodegenerative diseases including Parkinson's disease and dementia by identifying disease abnormalities before noticeable symptoms appear, according to an Article published Online First and in the October edition of The Lancet Neurology.
Previous research has shown that idiopathic, or inexplicable, IRBD could be an early predictor of neurodegenerative disorders in over half of patients. However, which patients with IRBD will develop these disorders is not known. Identification of patients at increased risk of developing these disorders would improve knowledge of disease progression at very early stages and be an opportunity to treat patients far earlier in their disease course.
An international team led by Alex Iranzo de Riquer from the Hospital Clinic of Barcelona, Spain, theorized that neuroimaging abnormalities typical of early Parkinson's disease might also occur in some patients with IBRD, and could be used to identify patients who might then be at increased risk of developing a degenerative brain disorder in the short term. Even before clinical symptoms are evident, striatal dopamine dysfunction** is a common dopamine transporter (DAT) imaging finding in Parkinson's disease, whilst hyperechogenicity of the substantia nigra (midbrain) is a typical finding in most patients with Parkinson's disease and dementia with Lewy bodies, and can be detected by transcranial sonography (TCS).
43 patients with IRBD were given two neuroimaging tests (DAT and TCS) at the start of the study. After 2.5 years, patients were assessed for neurodegenerative disorders.
27 (63%) patients showed low striatal dopamine transporters uptake or midbrain hyperechogenicity at the start of the study. Of these, eight (30%) developed a neurodegenerative disease. Five developed Parkinson's disease, two developed dementia with Lewy bodies, and one multiple system atrophy (a rare disorder that affects movement, balance, and other body functions such as bladder control). Patients with normal neuroimaging results at the start of the study remained disease free.
These findings, say the authors, show that neuroimaging techniques make it possible to identify neurodegenerative diseases at preclinical stages in patients with REM sleep disturbances.
They conclude that decreased striatal dopamine transporters uptake and midbrain hyperechogenicity are risk factors for developing neurodegenerative diseases in patients with IRBD, and might be useful predictive markers for identifying patients at increased risk of synucleinopathies (Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy).
Dr Alex Iranzo de Riquer, Hospital Clinic of Barcelona, Barcelona, Spain. E) AIRANZO@clinic.ub.es T) +34 93 227 5413 or +34 690 791 210 (mobile)
Or Via Communications Department, Hospital Clinic of Barcelona.
Marc de Semiar T) +34 93 227 57 00 E) mdesemir@clinic.ub.es
Alex Argemi T) +34 93 227 57 00 E) aargemi@clini.ub.es
For full Article see: http://press.thelancet.com/tlnsleep.pdf
Notes to Editors:
*REM sleep behaviour disorder (IRBD) is characterised by a loss of the normal muscle paralysis in REM sleep (the dream stage of sleep) that causes people to act out their dreams.
**A loss of dopamine (that helps control muscle movement) in the striatum part of the brain is the main cause of Parkinson's disease. Dopamine deficit begins several years before clinical symptoms appear.
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The Lancet Neurology