# Neuroprotective Effects of Molecular Hydrogen: A Critical Review.
> 分子状水素の神経保護効果に関する批判的レビュー


## Abstract

Molecular hydrogen (H2), though physiologically inert under normal conditions, exhibits notable biological activity in pathological states. This review consolidates evidence from preclinical and clinical studies on H2's protective roles across multiple nervous system disorders, including ischemia-reperfusion brain injury, traumatic injury, subarachnoid hemorrhage, neuropathic pain, neurodegenerative diseases, surgery- and anesthesia-induced cognitive impairment, anxiety, and depression. The authors examine H2 donor compounds and their pharmacokinetic profiles, and evaluate the efficacy and safety data available. Key protective mechanisms identified include suppression of oxidative stress, reduction of inflammatory signaling, inhibition of apoptosis, modulation of autophagy, and preservation of mitochondrial integrity and blood-brain barrier function. The review concludes that H2 represents a promising, low-risk approach for conditions such as ischemia-reperfusion brain injury, Parkinson's disease, and cognitive dysfunction syndromes.

### Mechanism

H2 exerts neuroprotection by scavenging reactive oxygen species, suppressing inflammatory pathways, inhibiting apoptosis, regulating autophagy, and preserving both mitochondrial function and blood-brain barrier integrity.

## Bibliographic

- **Authors**: Chen W, Zhang H, Qin S
- **Journal**: Neurosci Bull
- **Year**: 2021
- **PMID**: [33078374](https://pubmed.ncbi.nlm.nih.gov/33078374/)
- **DOI**: [10.1007/s12264-020-00597-1](https://doi.org/10.1007/s12264-020-00597-1)
- **PMC**: [PMC7954968](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7954968/)
- **Study type**: review
- **Delivery route**: mixed routes
- **Effect reported**: not assessed

## Delivery context

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 33078374. https://h2-papers.org/en/papers/33078374
> **Source**: PubMed PMID [33078374](https://pubmed.ncbi.nlm.nih.gov/33078374/)