It's possible your friend is starting to show signs of Karsacoff's syndrom, which is irreversable brain damage from severe alcohol abuse. Even if it's not that bad, problems with short term memory, personality changes, and inability to concentrate are all symptoms of heavy alcohol abuse. And if he's at the point of having withdrawal seizures if he doesn't drink, then it's very serious.

The best you can do is encourage him to seek treatment, including a medical detox, and stop drinking, although he probably won't go through with it, until he recognizes alcohol as a problem.

Good luck.

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