Quitting alcohol and brain health

Hi, I have a friend who drinks the equivalent of 10-12 drinks a day every day. Says he’s been doing this for the last 3 years. Doesn’t drink throughout the day, only after work and weekend evenings. If he stops cold turkey is he at risk for physical withdrawals? Also, how long will it take to get his brain to baseline as far as anxiety and all that goes? From my understanding frequently consuming alcohol increases anxiety levels, so how long for that effect to go away after stopping