There's probably a difference in degree, however. Alopecia Areata is much more uncommon, while regular male pattern baldness is very common.
There's also the fact that Alopecia Areata is actually more common in women, which I imagine exaggerates the distress compared to the more run of the mill MPB.
I realize you didn't mean to use a study on Alopecia Areata, but the difference in degree could be quite large.
I still think it applies though; the psychological effect of being bald probably doesn't care much about the underlying cause.