MPA, or Provera, is by far I think the most common form of synthetic progesterone used in the US in hormone replacement therapy preparations. It seems pretty clear that it probably does not provide neuroprotection so I wanted to post it for reference.
The Synthetic Progestin (MPA, Provera) is Not Neuroprotective
The ovarian hormone progesterone is neuroprotective in different experimental models of neurodegeneration.
In conclusion, our findings indicate that progesterone is neuroprotective against kainic acid excitotoxicity in vivo while the synthetic progestin MPA is not and suggest that progesterone metabolism to its reduced derivatives DHP and THP is necessary for the neuroprotective effect of the hormone.
MPA (Provera) Exacerbates Glutamate Toxicity
MPA pretreatment exacerbated neuron death induced by glutamate excitotoxicity as indicated by a 40% increase in neuron death determined by direct live/dead cell count
Collectively these results predict that the progestin formulation of hormone therapy will affect the vulnerability of the central nervous system to degenerative insults.
If you consider progesterone at all, it seems like considering the "real" thing and not the synthetic might be a good idea.