Low-Concentration Hydrogen Inhalation Suppresses Depression and Social Impairment from Blast-Induced TBI | Joint Research by MiZ and National Defense Medical College

A joint research group from MiZ Co., Ltd. and the National Defense Medical College revealed in 2018 that molecular hydrogen (H2) inhalation prevents social deficits and depression-like behaviors in mouse models of blast-induced traumatic brain injury (bTBI) caused by low-intensity explosions. Furthermore, in January 2026, MiZ and Keio University investigated hydrogen explosion accidents within the human body. They proposed that for social implementation, hydrogen inhalation devices should maintain an output concentration below the 'Practical Inhalation Threshold' of 10% by volume. This release reorganizes findings on neuroprotection and emphasizes the necessity of safe inhalation standards.

### Key Research Findings - bTBI causes Blood-Brain Barrier (BBB) disruption and oxidative stress, leading to depression, social withdrawal, and PTSD. - bTBI is difficult to diagnose via standard imaging (MRI/CT), leaving treatment methods unestablished. - Continuous inhalation of 4% H2 for seven days post-exposure nearly remitted behavioral abnormalities to levels comparable to healthy groups. - MiZ has patented the invention for 'Improving Human Post-Traumatic Stress Disorder (PTSD)' based on these results. - Low-concentration inhalation (<10% output) eliminates explosion risks and is suitable for long-term neuroprotective applications.

### Background: bTBI and the Role of Hydrogen Explosive shocks cause unique brain damage even without external trauma. Known as bTBI, it leads to neuropsychiatric symptoms like poor concentration and personality changes. Hydrogen selectively neutralizes hydroxyl radicals (•OH), the most toxic reactive oxygen species, and easily crosses the BBB to reach deep brain tissues. Regarding safety, MiZ announced in 2015 that hydrogen concentrations exceeding 10% in daily environments pose explosion risks. This 10% value is a practical threshold verified for inhalation environments, distinct from the theoretical 4% Lower Flammability Limit (LFL) defined in closed, static systems.

### Experimental Results and Safety Shift In mouse models exposed to 25kPa shockwaves, the non-hydrogen group showed significant depression and social avoidance. The 4% H2 group showed no such abnormalities. While therapeutic effects are clear, the market currently sees high-concentration devices (67–100% H2) linked to severe accidents, including internal body explosions. Data from the Consumer Affairs Agency of Japan includes reports of facial fractures and organ ruptures caused by hydrogen igniting via static electricity within the respiratory tract. MiZ and Keio University's 2026 study verified these risks, advocating for a shift to 'inherently safe' low-concentration designs to prevent such catastrophic injuries.