Has anyone listened to the DoseNation podcast?
I've heard the last 10, yeah there is a potential downside to 'use', esp. overuse.
The 'psychedelic state' is a tool, bit like hypnosis is a tool.
Some people on the 'scene' were probably 'reality challenged' before trying anything. I find the 'brain blood volume' thing a bit nutty. Its as though anyone over 6 feet tall would just about be comatose.
An interesting listen. Stay grounded...