Neuro-reparative potential of hyperbaric oxygen therapy in animal models of Alzheimer’s and Parkinson’s diseases: systematic review and meta-analysis

INTRODUCTION: This systematic review and meta-analysis explored the efficacy of Hyperbaric oxygen therapy (HBOT) in preclinical models of Alzheimer's disease (AD) and Parkinson's disease (PD). METHODS: Data were extracted as per PRISMA guidelines using specific search criteria, with bias assessed using SYRCLE guidelines. Random-effect models were used for meta-analyses of key outcomes, and forest plots were generated. Outcomes assessed included cognitive and motor performance, neuroinflammation, oxidative stress, mitochondrial function, apoptosis, and dopaminergic neuron survival. RESULTS: The PRISMA search yielded 8 studies (AD: 3; PD: 5) from a total of 8261 articles identified. A total of 308 animals were reported across the studies; however, 182 were included in the meta-analysis, as only animals from relevant treatment and corresponding control groups with extractable outcome data were eligible for quantitative analysis. HBOT significantly improved cognitive function (reduced escape latency, Standardized Mean Difference; SMD: -2.13), improved spatial memory, and reduced compensatory locomotor activity (decreased distance traveled, SMD: -6.94). The markers of neuroinflammation (lower TNF-α, higher IL-10), oxidative stress (SOD, MDA), mitochondrial biogenesis (SIRT1, PGC-1α, TFAM, VDAC), and anti-apoptotic markers (higher Bcl-xl, lower Bax) showed differences in post-HBO treatment. HBOT also preserved dopaminergic neurons in PD models. CONCLUSIONS: These preclinical findings support HBOT as a potential complementary neuroprotective therapy for AD and PD, warranting further clinical validation.