Because 5ar2 is also found in the human brain (http://www.hindawi.com/journals/au/2012/530121/tab3/) taking finasteride will have an effect on it due to allopregnanolone depletion (http://www.lf1.cuni.cz/Data/Files/PragueMedicalReport/pmr_110_2009_03/pmr2009a0025.pdf ; http://www.degruyter.com/view/j/hmbci.2010.1.issue-2/hmbci.2010.010/hmbci.2010.010.xml). Allopregnanolone is needed for neurogenesis, studying, stress control and probably many other stuff, if you start reading studies (http://www.ncbi.nlm.nih.gov/pubmed/20486040). Alzheimer's, Parkinson's and depression patients also have low levels of allopregnanolone. http://en.wikipedia.org/wiki/Allopregnanolone So stop taking it and hope you get your allopregnanolone back, because your neurons need it! - - - Updated - - - http://www.lf1.cuni.cz/Data/Files/PragueMedicalReport/pmr_110_2009_03/pmr2009a0025.pdf I don't understand why the link won't work in the first post. Try it here!