Self Medicating Anxiety with Alcohol

It sounds like your brother figured out how to treat his anxiety by self-medicating.  This is common and unfortunately leads to even more problems because as you've observed...alcoholism has developed.  Most treatment centers recommend at least 2-3 months of sobriety before treating anxiety.  Your brother needs to be sober so that he can learn new ways to cope.  He doesn't yet realize that exercise, looking at how he thinks, physiological changes, and maybe even medication could help him with anxiety.  Right now he probably thinks the only way he can lessen the anxiety is by drinking.  Hopefully with social support and understanding what emotions come up that make him want to drink, he can address his alcoholism and later his anxiety.  Good luck to the both of you.