There is something that needs to be stated about why Golden Dawn lodge officers (this includes the RR et AC and mythical Third Order) frown on drug use for magical purposes. Not only are drugs illegal (as an organization, we do not like having any meeting end with a police raid), drugs lead to random illuminations at best, delusions that you are spiritually advancing at worse.
It does not matter if drugs kill brain cells.
What matters is that drugs sensitizes the energy bodies, leaving one open to suggestion from any wandering entity that comes by. If you are lucky, they are higher in the chain than you are; if you are unlucky, they are less evolved than you are. Drugs also inflate the ego and lower passions.
Golden Dawn is about bringing a person to a certain energetic and spiritual place. The use of drugs in magic and spiritual development randomizes this process, and works against what Golden Dawn is trying to accomplish.
Our Magic is about control. It is not about visiting random spots in the universe, nor is it about making you feel better. Our Philosophy concerns controlled evolution. Randomness and the lack of controls works against what we are doing.
This is my official opinion as a lodge officer.