How Meditation Alters The Way Fluid Moves in The Brain, Aiding in Cleansing

Mindfulness meditation is widely known for its psychological benefits, such as stress reduction and improved attention. This study expands on this understanding by showing that meditation can also affect fundamental physical processes in the brain. The results indicate that focused attention meditation can modulate cerebrospinal fluid circulation in a manner similar to sleep, but while the person remains awake. This suggests that meditation may function as a non-pharmacological strategy to support brain cleansing and potentially protect against the effects of aging and neurodegeneration.

The brain has its own fluid circulation system, mainly composed of cerebrospinal fluid (CSF) and interstitial fluid. These neurofluids play an essential role in removing metabolic waste, distributing nutrients, and maintaining brain health.

Alterations in this circulation are associated with aging and neurodegenerative diseases such as Alzheimer's and Parkinson's. In particular, increased abnormal cerebrospinal fluid flow and its return movement through the cerebral aqueduct have been observed as signs of dysfunction in these states.

It is known that sleep exerts a strong influence on the circulation of neurofluids, promoting more efficient brain cleansing. During deep sleep, the flow of cerebrospinal fluid increases and becomes more organized, facilitating the removal of potentially toxic substances.

However, it is still unclear whether other states of consciousness, such as meditation, could produce similar effects while the person remains awake.

Mindfulness meditation, in particular, shares several physiological characteristics with sleep, such as reduced spontaneous mental activity and changes in breathing and alertness.

In this study, researchers investigated whether mindfulness meditation of the focused attention type, a practice in which the individual maintains sustained attention on an object, such as the breath, could modify neurofluid dynamics in a way similar to sleep and opposite to aging.

To this end, individuals with no prior meditation experience were compared to experienced meditators, evaluating their brains during different mental states, such as mind-wandering (when the mind wanders freely) and meditation proper.

The experiment used advanced magnetic resonance imaging techniques. To directly measure cerebrospinal fluid flow, phase-contrast magnetic resonance imaging was employed, which allows quantifying the speed and volume of cerebrospinal fluid passing through the cerebral aqueduct, a narrow channel that connects the brain's ventricles.

In addition, functional magnetic resonance imaging (BOLD) was used, a technique that detects fluctuations associated with brain activity and blood oxygenation, allowing observation of cerebrospinal fluid oscillations near the base of the skull and gray matter.

Participants were divided into three main groups: adults with no meditation experience assessed during ordinary daydreaming, adults with no experience assessed during daydreaming with breath control, and experienced meditators assessed both during daydreaming and during focused attention meditation.

This experimental design allowed for the separation of the effects of meditation itself from those caused solely by respiratory changes or task repetition.

The results showed that, in individuals with no meditation experience, there were no significant changes in cerebrospinal fluid flow in any of the conditions tested. In contrast, in experienced meditators, the practice of focused attention meditation reduced the total movement of cerebrospinal fluid through the cerebral aqueduct.

This reduction occurred primarily due to a decrease in the regurgitant flow of cerebrospinal fluid towards the head, a pattern opposite to that observed in aging and neurodegeneration. In other words, during meditation, cerebrospinal fluid moved in a more controlled and less disorganized manner.

Functional magnetic resonance imaging (fMRI) scans also revealed that, during meditation, there was an increase in slow fluctuations of cerebrospinal fluid near the junction between the brain and spinal cord.

These fluctuations were inversely related to gray matter activity, a pattern similar to that observed during deep sleep.

This finding suggests that mindfulness meditation may induce a specific physiological state during wakefulness, in which the brain enters a mode of operation favorable to the circulation of neurofluids and the maintenance of brain health.

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Neurofluid circulation changes during a focused attention style of mindfulness meditation

Bryce. Keating, David Vago, Kilian Hett, Ciaran Considine, Maria Garza, Caleb Han, Colin McKnight, Daniel O. Claassen, and Manus J. Donahue 

PNAS. December 3, 2025, 122 (49) e2504961122

https://doi.org/10.1073/pnas.2504961122

Abstract|:

Neurofluids, including cerebrospinal fluid (CSF) and interstitial fluid, circulate through regulated central nervous system pathways to clear cerebral waste and support brain health, with elevated CSF flow hyperdynamicity and regurgitation through the cerebral aqueduct associating with aging and neurodegeneration. Sleep exerts state-dependent effects on neurofluid circulation, yet similar modulation during unique waking states, such as meditation, remains underexplored. Notably, mindfulness meditation shares several regulatory features with sleep, with core meditation practices representing distinct arousal states. We investigated whether the focused attention (FA) style of mindfulness meditation modulates neurofluid dynamics directionally opposite to aging and consistent with sleep. Using phase-contrast MRI, we assessed absolute CSF flow and velocity through the aqueduct, and using blood oxygenation level–dependent (BOLD) MRI, we assessed CSF fluctuations near the cervicomedullary junction together with total supratentorial gray matter fluctuations. Assessments were repeated in meditation-naïve adults during mind wandering (MW) without (n = 13; repeatability controls) and with (n = 14; breath controls) respiration rate modulation and in adept meditators (n = 23) during MW and FA meditation. No aqueduct CSF flow changes were observed in control groups. In meditators, aqueduct absolute CSF flow motion decreased from MW to FA meditation (4.60 ± 2.27 mL/min to 4.17 ± 2.10 mL/min, P = 0.005) owing to reduced regurgitant cranially directed CSF flow velocity. On BOLD, this paralleled increased low-frequency (0.0614 to 0.0887 Hz) CSF fluctuations (P = 0.0138), which were inversely correlated with gray matter fluctuations during FA meditation. Findings suggest that mindfulness meditation may represent a nonpharmacological, waking state capable of modulating neurofluid dynamics in a directionally similar manner to sleep and opposite to aging and neurodegeneration.