The neuroprotective effects of this female hormone have been widely documented in recent years, including on this website and Headway News. Early-stage trials in humans yielded encouraging results, showing that progesterone was effective in reducing inflammation and inhibiting the death of cells.
On the basis of these results two large phase-three clinical trials were initiated in the United States; the PROTECT III trial and the SYNAPSE trial. PROTECT III was halted early, but a total of 1,195 patients in the early stages after TBI were recruited for SYNAPSE from trauma centres in 21 countries. 591 patients were administered with intravenous progesterone and 588 were given a placebo.
The recovery of the patients in both groups was then measured using the Glasgow Outcome Scale. The proportion with a favourable outcome (good recovery or moderate disability) was 50.4% with progesterone and 50.5% with placebo. This indicates no clinical benefit from the progesterone treatment.
After such high hopes these results are a huge disappointment and the authors suggest that the complexity and variability of brain injuries is the reason for the long history of failed TBI trials. Scientists will continue their efforts in other areas and we can only hope for better results in future.
Reference
Skolnick, B. et al. (2014) A clinical trial of progesterone for severe traumatic brain injury. New England Journal of Medicine, (26), 2467-76.
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