A recent study provided evidence that only 5AR type I is important in effects on the hair follicle…
ncbi.nlm.nih.gov/sites/entre … s=16849416
“That only SRD5A1 haplotypes were associated with hirsutism suggests that only this isoform is important in the hair follicle.”
If this is true, then the fact the finasteride does in fact work to retore hair, is evidence that it is in fact blocking 5AR type I, and thus effecting the metabolism of brain steroids.
The article also mentions the fact that there are several variants of 5AR type I (7 single-nucleotide polymorphisms, in the study). Some variants, I presume, are more easily inhibited than others…
Does this then mean that we should expect a direct link between finasteride efficacy in restoring hair growth and the extent to which one experiences detrimental mental health effects (i.e. brain fog)?