Sleep Prevents Alzheimer's Disease
Global brain activity as observed on fMRI tends to be associated with weaker cerebrospinal fluid flow in brains of individuals with Alzheimer's disease risk or related toxin build-up. Evidence of sleep-dependent low-frequency (<0.1 Hz) global brain activity is thus observed in the clearance of Alzheimer's disease-related toxin build-up as per a study at The Pennsylvania State University, published in the open-access journal PLOS Biology.
The cerebrospinal fluid flow in healthy controls was strongly linked with this neuronal activity when compared to higher risk groups and patients. These findings could serve as a potential imaging marker for clinicians in evaluating patients.
‘Global brain activity as observed on fMRI tends to be associated with weaker cerebrospinal fluid flow in brains of individuals with Alzheimer's disease risk or related toxin build-up. It was also demonstrated that sleep-related brain activity was associated with clearing toxic brain proteins and preventing Alzheimer's disease. These findings could serve as a potential imaging marker for clinicians in evaluating patients.’
Alzheimer's disease (AD) is a neurodegenerative disease that leads to gradual memory loss and behavioral changes. It is characterized by the formation of beta-amyloid plaques in the brain tissues, years before the actual symptoms occur.
The glymphatic system of the brain plays a crucial role in clearing these toxins. Earlier studies have shown that the sleep-dependent global brain activity, when coupled by cerebrospinal fluid flow, is essential for the efficiency of the glymphatic system. br>
The study team utilized 118 subjects in the Alzheimer's Disease Neuroimaging Initiative project to measure this global brain activity and cerebrospinal fluid flow and compared it with behavioral data.
The resting-state fMRI sessions were done two years apart for comparing the findings with neurobiological and neuropsychological markers related to Alzheimer's disease, such as levels of the toxic protein amyloid-β.
It was found that the strength of the connection between brain activity and cerebrospinal fluid flow was weaker in individuals at a higher risk or who had already developed Alzheimer's disease. Moreover, this weaker connection was associated with higher levels of amyloid-β and disease-related behavioral measures two years later.
The study thereby presents an important role for sleep-dependent global brain activity in the clearance of brain waste, and its connection to cerebrospinal fluid flow could be helpful as a future marker for clinical evaluation.
"The study linked the coupling between the resting-state global brain activity and cerebrospinal fluid flow to Alzheimer's disease pathology. The finding highlights the potential role of low-frequency (<0.1 Hz) resting-state neural and physiological dynamics in the neurodegenerative diseases, presumably due to their sleep-dependent driving of cerebrospinal fluid flow to wash out brain toxins. Future studies are warranted to fully understand the global brain activity and associated physiological modulations and their role in glymphatic clearance and neurodegenerative diseases," says Dr. Liu.
Source: Medindia