Taking propecia/dutasteride is practically the same thing as ADT. Your removing DHT so I kind of fail to see how this study does not relate to taking you know anti-androgens for male pattern baldness. I mean propecia was originally a prostate drug for god sakes how much more a connection could we get? This study absolutely applies to propecia/dutasteride too. Its just prostate cancer they probably take stronger drugs that inhibit T and other androgens along with DHT.
A lot of the men were very old though so some, of course, would get dementia regardless hard to say how strong the link is.