How has molecular hydrogen been studied in neurodegenerative conditions?
17 papers. Randomized human trials: 4. Human comparative studies, including studies without reported randomization: 3. Human single group and observational studies: 3. Animal studies, including studies with cell experiments: 7.
Abstracts returned by the Europe PMC MED and PMC title and abstract query were reviewed. Human original studies and systematic reviews including human evidence have no lower year limit; animal and cell original studies start on January 1, 2024. Groups are ordered by first publication date, newest first.
Checked 2026-10-29 · 73 records searched
Randomized human trials4
Twenty people with Parkinson’s disease taking levodopa were randomized double blind to approximately 6.5% hydrogen or placebo air for one hour twice daily over 16 weeks. Disease scales and inhalation adherence were recorded.
Neurol Sci · 2021 · PMID 34319514
Twenty people with Parkinson’s disease inhaled approximately 1.2% to 1.4% hydrogen air or placebo for ten minutes twice daily over four weeks in a double blind randomized crossover study. An eight week washout separated periods; smell, nonmotor symptoms, daily living and urinary 8 OHdG were assessed.
Med Gas Res · 2018 · PMID 30713666
Seventy three people with mild cognitive impairment were randomized double blind to approximately 300 mL of hydrogen rich or placebo water daily, with cognitive scales after one year. The accompanying older mouse experiments are not counted as separately included animal evidence.
Curr Alzheimer Res · 2018 · PMID 29110615
Seventeen people with Parkinson’s disease taking levodopa were randomized double blind to hydrogen water in nine or placebo water in eight. Participants drank 1,000 mL daily for 48 weeks, with Unified Parkinson’s Disease Rating Scale measurements.
Mov Disord · 2013 · PMID 23400965
Human comparative studies, including studies without reported randomization3
Records of 273 Alzheimer’s disease patients compared donepezil plus hydrogen oxygen inhalation in 138 people with donepezil in 135. Cognitive and daily living scales and P300 event related potentials were assessed.
Medicine (Baltimore) · 2023 · PMID 37505148
Eight Alzheimer’s disease patients inhaled 3% hydrogen for one hour twice daily over six months in an open pilot study. Cognitive scores were compared with unexposed patients, alongside hippocampal tract MRI and one year of follow up after inhalation ended.
Pharmaceuticals (Basel) · 2023 · PMID 36986533
Human measurements in 28 healthy adults and 37 people with Parkinson’s disease examined breath hydrogen after hydrogen water or lactulose. The older rat experiments in the same report are not separately included; the human component did not compare disease progression.
Med Gas Res · 2012 · PMID 22608009
Human single group and observational studies3
A Parkinson’s disease case report describes body bending and hand tremor during molecular hydrogen inhalation. Gas concentration, duration and total case count are not specified in the abstract.
Med Gas Res · 2024 · PMID 39073335
A nonrandomized single group study enrolled 54 community dwelling adults for four weeks of hydrogen gas inhalation, measuring white cells, oxidative markers and dementia related blood biomarkers. Enrollment was not restricted to diagnosed Alzheimer’s disease.
Antioxidants (Basel) · 2023 · PMID 37371971
Eighteen people with Parkinson’s disease received daily hydrogen water plus photobiomodulation for two weeks in an uncontrolled pilot study. Disease scales and adverse events were recorded; hydrogen was not studied alone.
Medicine (Baltimore) · 2021 · PMID 33530211
Animal studies, including studies with cell experiments7
5xFAD Alzheimer model and wild type mice inhaled 2% hydrogen for one hour daily over four weeks. Hippocampal reactive oxygen species, ATP, amyloid and serum cytokines were analyzed; animal n is not stated in the abstract.
Antioxidants (Basel) · 2026 · PMID 41897548
Four randomized groups of 14 5xFAD and 15 wild type mice received 3% hydrogen gas or vehicle for 60 days. Maze behavior and hippocampal and astrocyte ammonia, hydrogen peroxide and inflammatory markers were measured.
Int J Mol Sci · 2025 · PMID 40725167
An Alzheimer mouse model was used to assess nanocomposites that generate hydrogen under near infrared illumination. Brain delivery, inflammation and cognition were examined. This differs from ordinary inhalation or drinking water; animal n is not reported in the abstract.
Small · 2025 · PMID 39989154
Male C57BL/6 mice with induced vascular dementia received hydrogen rich drinking water or no hydrogen, alongside sham controls. Behavior, hippocampal tissue, T cells and transcriptomes were assessed; animal n is not stated in the abstract.
Antioxidants (Basel) · 2025 · PMID 39857445
Zebrafish with aluminum chloride induced Alzheimer like pathology received hydrogen rich water from a nanobubble device. Behavior, tissue, reactive oxygen species and gut microbiota were examined; animal n is not stated in the abstract.
Front Aging Neurosci · 2024 · PMID 39839307
SAMP8 and SAMR1 mice received hydrogen rich or placebo jelly from six weeks of age for 26 to 28 weeks. Behavioral and memory tests and brain inflammatory markers were assessed; animal n is not reported in the abstract.
Behav Brain Res · 2025 · PMID 39522774
Artificial nanoreactors generating hydrogen under near infrared light were tested in Alzheimer model mice, measuring reactive oxygen species and tau phosphorylation. Delivery differs from ordinary gas inhalation; animal n is not stated in the abstract.
Bioact Mater · 2024 · PMID 39280581
Excluded 56 of 73 records: no abstract (2), narrative or mechanistic review or commentary (27), retracted paper or retraction or concern notice (6), animal or cell study before 2024 (14), direct population or molecular hydrogen intervention outside topic scope (7).
View the search query
TITLE_ABS:("molecular hydrogen" OR "hydrogen gas" OR "hydrogen inhalation" OR "inhaled hydrogen" OR "hydrogen oxygen" OR oxyhydrogen OR "hydrogen rich") AND TITLE_ABS:(Alzheimer* OR Parkinson* OR dementia OR dyskinesia) AND (SRC:MED OR SRC:PMC) AND FIRST_PDATE:[* TO 2026-10-29]
Search Europe PMCFrequently asked questions
How many papers directly studied people?
There are 10 human original studies. Counts refer to papers and may include follow up reports from the same participants or overlap with reviews.
Which populations and methods are distinguished?
Alzheimer’s disease, Parkinson’s disease, mild cognitive impairment and animal models are distinguished. Gas inhalation, drinking water, jelly ingestion and experimental hydrogen generating nanomaterials are identified separately, including combined interventions.
Which publication years are included?
Human studies have no lower publication year limit through the checked date. Animal and cell studies start in 2024, including 7 animal studies and 0 cell only studies.