What do you do when your friends brains have been replaced with swiss cheese by aliens?

I have 2 friends I met in collage, and 1 I met in university….we usually meet on a somewhat regular basis. Over the past month the conversations we have had that they have initialized Have had a very noticeable drop in quality….

The latest one today is the worst… I have NO interest in the “Man, you wouldn’t believe the hot chick I saw today…I would totally “bang” her…” conversation, So I just got up and left.

I have reason to believe this change is somehow caused by a 4th person brought into the group…I have had limited contact with this person… But the “scent” of drugs is in the air…

I have little issues with users…“to reach your own” But I don’t like to associate with people wile they are “buzzing”...If my friends decide to travel this path….

I’m not sure how to address this…..I may just cut my losses and move on.

Any help would be appreciated…