In a pilot, double blind, cross over clinical trial, we are going to assess the effect of boswellia serata extract on neurocognitive rehabilitation following closed head injuries. We, prospectively, recruit 40 patients admitted with initial diagnosis of diffuse axonal injury. The patients are assigned in two groups. One group will receive Boswellia serrata extract, 400mg, 3 times a day, while the other group will receive placebo for 6 weeks. Then, the patients will be crossed over alternative intervention for another 6 weeks period. Neuro-cognitive function tests including Disability Rating Scale (DRS), the Glasgow outcome Scale/Extended (GOSE), and the Mini-mental Status Test (MMSE) are applied 1-2 weeks, 6 weeks, and 12 weeks after beginning of the intervention.