Concerned about my 33 year old that just developed a very bad stutter. Any idea what can be causing his sudden stuttering?

Concerned about my 33 year old that just developed a very bad stutter. Any idea what can be causing his sudden stuttering? I caught up with an old buddy of mine yesterday after not seeing him for a few months. Immediately I realized he was stuttering to a very extreme amount. In his twenties he had a very slight stutter. Although I didn’t ever consider it a stutter. It just sounded like he was talking nervously, or unsure/hesitant. But not an obvious stutter, and he, nor his wife, friends or myself pointed it out. But last night it was so bad that it would take him 5-10 tries before getting a word/sentence out. A few times would even acknowledge it and say “stupid stuttering” amid all of it.   For some context, *  He is a relatively heavy drinker (has been for the last 7 or 8 years) * From 2020-2023 was doing MDMA pretty often (at some points once a week or month) * Works outside all day in landscaping * Has dealt with a lot of trauma in his life (lost his brother and a couple friends from fentanyl overdose but has always been a very positive person)