Impaired cerebral microcirculation in isolated REM sleep behaviour disorder

Area of Science:

• Neuroscience
• Neurology
• Radiology

Background:

• Parkinson's disease and related parkinsonisms involve neurodegeneration affecting brain nuclei regulating mood, sleep, and cognition.
• These nuclei also control cortical blood flow, crucial for adjusting oxygen supply to neural activity.
• Isolated REM sleep behaviour disorder is a potential prodromal phenotype of α-synucleinopathies.

Purpose of the Study:

• To investigate microvascular flow disturbances in the cortex of patients with isolated REM sleep behaviour disorder.
• To determine if these disturbances are linked to impaired central blood flow control.
• To assess the association between cortical blood flow abnormalities and cognitive performance.

Main Methods:

• Dynamic susceptibility contrast MRI was used to assess cerebral blood flow distribution in the cortex.
• 20 patients with isolated REM sleep behaviour disorder and 25 healthy controls were studied.
• Cognitive function was evaluated using the Montreal Cognitive Assessment and Mini Mental State Examination.

Main Results:

• Patients with isolated REM sleep behaviour disorder exhibited profound hypoperfusion and microvascular flow disturbances throughout the cortex compared to controls.
• These microvascular abnormalities were observed in cortical areas critical for language, visual processing, and recognition.
• Impaired cognitive performance correlated with the observed microvascular flow disturbances.

Conclusions:

• Cortical blood flow abnormalities, likely due to impaired neurogenic control, are present in patients with isolated REM sleep behaviour disorder.
• These abnormalities are associated with cognitive dysfunction in this patient group.
• Restoring perivascular neurotransmitter levels may help maintain cognitive function in this prodromal parkinsonism phenotype.