@CalamityJane,
Well, I think that alcohol in excess causes brain damage, and, over time, this can produce changes in personality over and above the addiction thing.
Although, it's interesting....ever met anyone with Korsakoff's...(a dementia common in alcoholics and older anorexics..due to vitamin B deficiency)?
Often the apparent personality remains there...all the mannerisms and ways of relating...but there's just no content.