A 48-year-old male is evaluated in an outpatient psychiatric clinic 10 days after completing medically supervised alcohol detoxification. He reports persistent depressed mood, anhedonia, insomnia, fatigue, poor concentration, and feelings of worthlessness since stopping alcohol. He had been drinking 8-12 beers daily for 3 years prior to detoxification. He denies suicidal ideation. He reports that he first noticed feeling depressed approximately 18 months ago and states, "I started drinking more to deal with feeling down." However, collateral information from his wife reveals that his heavy drinking began approximately 4 years ago and his personality and mood changes became noticeable about 2 years into his heavy drinking. She does not recall any depressive episodes before his drinking escalated. He has no prior psychiatric history and no family history of mood disorders. What is the MOST likely diagnosis at this time?