you probably mean alopecia areata -
was he diagnosed a having alopecia, or is he just assuming that he lost hair so thats what it is?
alopecia is most commonly one or more circular bald spots usually about quarter sized
if it was after aas use, it may have been a Telogen Effluvium (a shock fallout), which is a diffuse shed all over his head including areas not usually associted with male pattern baldness.
which does his sound most like?