Neuroimaging Offers Early Detection of Parkinson's Disease

Rapid eye movement (REM) sleep disturbances were found by investigators in 2006 to constitute an early marker of neurodegenerative diseases. A new study published September 15, 2010, in the early online publication of the journal the Lancet Neurology by the same researchers applies neuroimaging techniques to identify patients with REM sleep disturbances who will develop neurodegenerative disorders over the short term.

The first author of both article is Dr. Alex Iranzo, a physician in the neurology department of the Hospital Clinic in Barcelona (Spain), who is also an investigator of the Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS; Barcelona, Spain), and a member of the Multidisciplinary Sleep Disturbances Unit. The study has been carried out in the setting of the Neurodegenerative Diseases CIBER (Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas [CIBERNED]; Seville, Spain), and has received the collaboration of the neurology department of the Innsbruck Medical University (Austria).

One of the challenges of modern medicine is the diagnosis of diseases before they develop clinical manifestations such as tremor or dementia. Neurodegenerative disorders begin in latent periods during which the cells suffer degeneration but clinical manifestations are not yet observed. In this context, the degenerative process advances, and neuropathological changes affect the nervous system. The new data contributed by the investigators of the Hospital Clínic-IDIBAPS make it possible to identify the disease at preclinical stages in patients with REM sleep disturbances.

In earlier research of this same team, 45% of the patients studied had developed a neurodegenerative disorder five years after diagnosis of the sleep disturbance. All of them were over 60 years of age and presented REM sleep disturbances in the form of nightmares in which they called out, cried, or showed body movements. The new study goes beyond this point and presents the data relating to the tracking of 43 new patients during two years and a half after undergoing the neuroimaging tests. The 123I-fluoropropyl (FP)-carbomethoxy-iodophenyl-tropan (CIT) single photon emission computed tomography (SPECT) imaging technique makes it possible to identify striatal dopamine dysfunctions typical of brain substantia nigra pathology, which can degenerate towards Parkinson's disease. Transcranial ultrasound identifies structural alterations of the substantia nigra such as increased iron presence, before Parkinsonism gives rise to clinical manifestations.

The study described how 19% of the patients had developed a neurodegenerative disorder in the two and a half years following the neuroimaging tests. Of these subjects, five developed Parkinson's disease, two developed Lewy body dementia, and one patient developed multisystemic atrophy. All of them belonged to the group of 27 patients (62.8%) showing low FP-CIT uptake at SPECT and/or hyperechogenicity in the substantia nigra in transcranial ultrasound. In other words, none of them had yielded normal results in the neuroimaging tests. In turn, the patients with normal neuroimaging findings revealed no neurologic disorders after 2.5 years of follow-up.

The investigators concluded that the neuroimaging methods make it possible to identify patients with REM sleep disturbances who are at high risk of early development of a neurodegenerative disorder such as Parkinson's disease. This will help improve tracking the progression of these diseases and test drugs that might modify their course and initiate early therapy, once the clinical diagnosis is established.

Related Links:
Institut d'Investigacions Biomèdiques August Pi i Sunyer
Innsbruck Medical University
Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerative