What does the story have to do with alcoholism?

The story suggests that Poe was greatly interested in the
causes of evil, for his analysis of his nameless narrator’s motivation is almost equal
to the story itself, particularly in the opening pages. Poe offers two major
explanations for the narrator’s “alteration for the worse” (paragraph 6). The first is
alcoholism. The second, and the more interesting, is what Poe calls “perverseness.” A
similar concern with such evil may also be found in famous works like Browning’s
“Porphyria’s Lover” and Stevenson’s “Dr. Jekyll and Mr. Hyde,” both of which demonstrate
that evil and good are sometimes inseparable. Perhaps it is the alcoholism side of the
person doing the acting. Poe’s story overweights his analysis, however, but this most
interesting story is one in which the narrative blends with moral and psychological
concerns.