Key Takeaway
HBOT shows consistent improvements in cognitive function across multiple domains, particularly in patients with traumatic brain injury, stroke, and age-related cognitive decline.
Summary
This systematic review evaluated the evidence for hyperbaric oxygen therapy's effects on cognitive function across a range of neurological and non-neurological conditions. The authors systematically searched the literature for clinical studies that used validated neuropsychological assessments to measure cognitive outcomes before and after HBOT courses.
The review found that HBOT was associated with improvements across multiple cognitive domains, including attention, memory, executive function, and information processing speed. The most robust evidence came from studies in traumatic brain injury (TBI) and post-stroke populations, where patients showed measurable gains on standardized cognitive tests following HBOT protocols. Studies in aging populations and those with mild cognitive impairment also reported positive trends, though with smaller sample sizes.
The authors noted considerable variability in study protocols, including differences in pressure levels, session counts, and timing of assessments. While the overall direction of evidence was positive, the heterogeneity and lack of large-scale RCTs limited the strength of conclusions. The review highlighted that HBOT's cognitive benefits likely stem from enhanced cerebral oxygenation, neuroplasticity, and reduced neuroinflammation, and called for standardized protocols in future research.
Methods
Systematic search of PubMed, Scopus, and Web of Science databases for studies examining the effect of HBOT on cognitive functions. Included studies used validated neuropsychological tests (e.g., MMSE, MoCA, Trail Making Test, CANTAB) to assess cognitive outcomes. Studies were categorized by clinical condition (TBI, stroke, aging, fibromyalgia, post-COVID, etc.). Quality was assessed using established risk of bias tools. Narrative synthesis was performed due to heterogeneity preventing formal meta-analysis.
Key Results
- The majority of included studies reported significant improvements in at least one cognitive domain after HBOT
- TBI studies showed the most consistent improvements, particularly in memory and attention
- Stroke recovery studies demonstrated improvements in executive function and processing speed
- Studies in older adults showed positive trends in global cognitive scores (MMSE/MoCA)
- Typical effective protocols used 1.5-2.0 ATA for 40-60 sessions
- Benefits were observed across mild, moderate, and severe cognitive impairment
- Some studies reported sustained improvements at follow-up assessments weeks to months post-treatment
Limitations
- Significant heterogeneity in study designs, HBOT protocols, and cognitive assessments used
- Many studies had small sample sizes (n < 50)
- Lack of adequate sham controls in several studies, making placebo effects difficult to rule out
- Formal meta-analysis was not possible due to protocol and outcome variability
- Limited data on long-term durability of cognitive improvements
- Publication bias may have skewed results toward positive findings