Researchers have discovered that by modulating a person’s respiratory intake of carbon dioxide, the brain’s intrinsic “waste removal” mechanism can be significantly amplified.
This pioneering proof-of-concept investigation, spearheaded by neuroscientists affiliated with the University of New Mexico (UNM) and The Mind Research Network in the United States, presents a compelling prospect concerning a vital clearance system that was only delineated within the human physiology within the past decade.
The findings intimate that transiently elevating blood carbon dioxide concentrations might facilitate the expulsion of deleterious waste products from the brain, potentially averting neurodegenerative conditions linked to these toxins, such as Parkinson’s or Alzheimer’s disease.
In a series of recent experimental trials involving both healthy individuals and those diagnosed with Parkinson’s disease, scientists observed that the administration of rhythmic carbon dioxide-enriched air pulses for abbreviated durations served to enhance the functionality of the brain’s waste-expulsion pathway.
The precise underpinnings of this phenomenon remain elusive to the scientific community. However, it is understood that fluctuations in carbon dioxide levels can induce vasodilation and vasoconstriction in cerebral blood vessels. This pulsatile vascular activity may, in turn, stimulate the adjacent flow of cerebrospinal fluid – the clear, protective liquid that envelopes the brain and spinal cord, often referred to in relation to the glymphatic system.
Typically, during periods of sleep, subtle waves of cerebrospinal fluid progressively cleanse the brain of accumulated metabolic waste. Nevertheless, sleep disturbances are a prevalent symptom in Parkinson’s patients, potentially contributing to the aggregation of improperly folded proteins.
Furthermore, cerebral blood flow regulation appears to be compromised in individuals with Parkinson’s disease, and the brain in such cases often exhibits elevated concentrations of these potentially toxic misfolded proteins.
Consequently, some researchers have posited that the brain’s waste disposal system plays a foundational role in the pathogenesis of these neurological disorders.
Current scientific endeavors are focused on identifying methods to actively modulate the glymphatic system to preserve optimal brain function. The strategic manipulation of carbon dioxide levels has emerged as a promising avenue to achieve this objective.
“Our team engaged in brainstorming sessions to ascertain how we might augment this physiological response,” explains Sephira Ryman, a neuropsychologist at UNM. “It was at this juncture that we recognized the potential to replicate, in a conscious state, the glymphatic clearance processes typically associated with deep sleep by employing intermittent carbon dioxide exposure.”
During the experimental phase, 63 elderly volunteers, 30 of whom had been diagnosed with Parkinson’s disease, underwent MRI-BOLD brain imaging. Their participation involved cyclical inhalation of brief periods of elevated carbon dioxide, lasting approximately 35 seconds, interspersed with exposure to normal atmospheric air.
This therapeutic intervention, termed intermittent hypercapnia, results in a temporary elevation of blood carbon dioxide concentrations. In both the healthy control group and the Parkinson’s patient cohort, this procedure elicited discernible alterations in cerebrospinal fluid dynamics.
In a subsequent experiment involving 10 participants, 5 of whom had Parkinson’s disease, subjects engaged in three distinct 10-minute sessions of intermittent hypercapnia. Blood carbon dioxide levels were subsequently ascertained at intervals of approximately 45, 90, and 150 minutes post-intervention.
Both the healthy participants and those with Parkinson’s disease demonstrated an enhancement in cerebrospinal fluid circulation and glymphatic waste removal efficiency. Moreover, an increased presence of brain-derived waste products was detected in their bloodstream, indicative of improved clearance.
Evidence of amyloid-beta proteins, a recognized biomarker for Alzheimer’s disease, was observed in the blood of one study participant. Following the intermittent hypercapnia sessions, their plasma concentrations of these implicated toxins exhibited a substantial increase.
“Intermittent hypercapnia may possess the capacity to facilitate the clearance of peptides and proteins implicated in Alzheimer’s pathology, thereby underscoring its potential as a disease-modifying therapeutic strategy for individuals afflicted with Alzheimer’s,” the study’s authors propose.
However, it remains undetermined whether these observed changes are enduring or contribute significantly to the amelioration of disease pathology.
While cerebro-toxic waste products are intrinsically linked to Alzheimer’s and Parkinson’s diseases, their precise role – whether as causative agents or mere byproducts of pathological processes – is yet to be definitively established.
Ryman and her research associates are presently exploring the potential influence of abdominal breathing techniques, prevalent in practices such as yoga, tai chi, and qigong, on carbon dioxide levels and subsequent brain clearance mechanisms in a comparable fashion.
This research was formally published in the esteemed journal NPJ Parkinson’s.
