Low Blood Flow in the Brain May Be an Early Sign of Parkinson’s Disease

Summary: A new study reveals a potential link between REM sleep behavior disorder and an increased risk of developing Parkinson’s disease. Researchers say the sleep disorder alters cerebral blood flow, leading to a lack of oxygen in brain tissue. This, in the long term, may increase Parkinson’s risk.

Source: Aarhus University

Patients who suffer from REM sleep behavior disorder have altered blood flow in the brain, which can lead to a lack of oxygen in the brain tissue. In the long term, this may cause symptoms of Parkinson’s disease. This is shown by research from Aarhus University and Aarhus University Hospital.

Do you sleep restlessly and flail your arms and kick out in your sleep? This could be a sign of a disorder associated with diseases of the brain. Researchers from AU and AUH have examined whether the sleep disorder RBD – which is also known as Rapid Eye Movement Sleep Behaviour Disorder – may be an early sign of Parkinson’s disease.

“We can see complications in the small blood vessels of the brain in patients with RBD, although these patients don’t otherwise have any symptoms and the brain doesn’t show other signs of disease,” says Simon Fristed Eskildsen, who is behind the study.

He explains:

“We believe that the same disease processes that cause disrupted sleep also affect the ability to control the blood flow in the brain, which can lead to a lack of oxygen in the brain tissue. Over time this will gradually break down the brain tissue and cause symptoms that we see in Parkinson’s disease.”

Monitored while asleep

The changes in the brain are associated with reduced neurotransmitters, meaning that nerves in the brain have trouble controlling the blood vessels.

“A medical treatment would be able to restore the neurotransmitter and control of the blood vessels, thereby helping to maintain the cognitive function of patients who show early signs of Parkinson’s disease,” explains the researcher.

Twenty RBD patients aged 54-77 years and 25 healthy control subjects aged 58-76 participated in the study. The participants in the study were monitored in a sleep laboratory, where they had their EEG (electrical activity in the brain), EOG (eye movements), EMG (muscle activity) and ECG (electrical activity in the heart) measured during sleep.

This shows a brain
Do you sleep restlessly and flail your arms and kick out in your sleep? This could be a sign of a disorder associated with diseases of the brain. Image is in the public domain

“The patients and the control subjects were tested cognitively and MRI scanned, and the results revealed low blood flow and flow disturbances in the small blood vessels in the brain in the patients compared with the control group. In the patients, these flow disturbances seen in the cerebral cortex were associated with language comprehension, visual construction and recognition – this was also associated with reduced cognitive performance,” says last author of the study, Nicola Pavese.

The researchers will now investigate whether the reduced blood flow in the brain deteriorates over time and how it is linked to the symptoms of Parkinson’s disease. The hope is that it will be possible to use the method to predict the disease in patients with sleep disorders in order to then prevent the symptoms at an early stage.

The results have just been published in the scientific journal Brain.

Parkinson’s disease

There are 7300 patients with Parkinson’s disease in Denmark. Symptoms are slow movements, often with shaking, together with muscular rigidity. Parkinson’s disease is a chronic condition that continues to worsen over time. About half of the patients experience cognitive decline early in the disease. The disease is somewhat more common in men than in women. Parkinson’s disease occurs because the brain lacks dopamine. It primarily affects adults and the first signs most often appear between the ages of 50-70.

Background for the results

The study is a clinical trial.

The study is a collaboration between Aarhus University, Aarhus University Hospital and the University of Barcelona, Hospital Clínic de Barcelona.

Funding: The study was funded by the Danish Council for independent Research and the Instituto de Salud Carlos III in Spain.

About this Parkinson’s disease research news

Source: Aarhus University
Contact: Simon Fristed Eskildsen – Aarhus University
Image: The image is in the public domain

Original Research: Open access.
Impaired cerebral microcirculation in isolated REM sleep behaviour disorder” by Simon Fristed Eskildsen et al. Brain


Impaired cerebral microcirculation in isolated REM sleep behaviour disorder

During the prodromal period of Parkinson’s disease and other α-synucleinopathy-related parkinsonisms, neurodegeneration is thought to progressively affect deep brain nuclei, such as the locus coeruleus, caudal raphe nucleus, substantia nigra, and the forebrain nucleus basalis of Meynert.

Besides their involvement in the regulation of mood, sleep, behaviour, and memory functions, these nuclei also innervate parenchymal arterioles and capillaries throughout the cortex, possibly to ensure that oxygen supplies are adjusted according to the needs of neural activity.

The aim of this study was to examine whether patients with isolated REM sleep behaviour disorder, a parasomnia considered to be a prodromal phenotype of α-synucleinopathies, reveal microvascular flow disturbances consistent with disrupted central blood flow control.

We applied dynamic susceptibility contrast MRI to characterize the microscopic distribution of cerebral blood flow in the cortex of 20 polysomnographic-confirmed patients with isolated REM sleep behaviour disorder (17 males, age range: 54–77 years) and 25 healthy matched controls (25 males, age range: 58–76 years). Patients and controls were cognitively tested by Montreal Cognitive Assessment and Mini Mental State Examination.

Results revealed profound hypoperfusion and microvascular flow disturbances throughout the cortex in patients compared to controls. In patients, the microvascular flow disturbances were seen in cortical areas associated with language comprehension, visual processing and recognition and were associated with impaired cognitive performance.

We conclude that cortical blood flow abnormalities, possibly related to impaired neurogenic control, are present in patients with isolated REM sleep behaviour disorder and associated with cognitive dysfunction.

We hypothesize that pharmacological restoration of perivascular neurotransmitter levels could help maintain cognitive function in patients with this prodromal phenotype of parkinsonism.

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