How much alcohol does it take to damage the brain?

[choisir]

I know the real answer is anything above 0, but still...

SWIM isn't addicted, however it being summer SWIM has started going out on a more regular basis, where "going out" = "getting smashed" amongst his circle of friends.

However SWIM feels a bit whacked out even when sober. He has trouble remembering (what should be) stored information (for example, a family member's phone number) and feels like it takes longer to do things like logic puzzles, sudoku, etc.

It is hard for SWIM to tell whether the alcohol is the cause or whether it's just a general lack of intellectual stimulation (SWIM is on summer holiday).

SWIM has "abstained" for the past few weeks and feels slightly better. However of course he can't tell whether that's due to a placebo effect.

Can 3 or 4 units every other day for a month really mess up your brain like that?

Thanks