I don't like a lot of McKenna's theories. The word "shaman" is such a loaded term these days. Shamans come from Siberia. How this term came to be applied to neo-tribal mysticism and anyone who believes in it is beyond me. I live on the west coast a lot of the native groups here call them "plastic shamans". It's always white people looking for a quick fix to spirituality. They pay hundreds of dollars to join apprenticeships that have no real power. If you want to connect to the earth, then just go out into the woods and meditate there. Plenty of messages will come to you. You don't need charlatants and thousands of dollars to do it. [/rant]
Anyway... to answer the OP's question, I wouldn't frame this as a 'shamanic' issue. I would, however, say that a lot of people with mental health issues as well as addicts are often extremely sensitive people who have been exposed to intense environments that they cannot handle. The repeated trauma leads people to seek answers, or self-medication, through narcotics. These sensitive people almost always have some kind of psychic ability, like clairvoyance, clairaudience, etc. They lack the support mechanisms to really delve into what it is they are seeing and experiencing. These sensitives have not been trained in proper boundaries, so they become over-exposed to intense forces, and they often don't realize or take for granted that other people are not experiencing what they are.
Schizophrenia is a real mental illness. Sufferers experience sensory perceptions that have a negative impact on their function and that try to manipulate them into doing things against their will. I've been able to see auras since birth and my life has been filled with paranormal events; I thought I was crazy until I met another clairvoyant who was seeing the same stuff as me at the same time, and could describe it in intimate detail. Unlike schizophrenics, the things I see don't try to manipulate me - they are just phenomena that I am observing and can make qualitative judgments about. When I walk away from what I'm observing, I no longer see it or experience it. I've been around schizophrenics. Their auras always have disturbances that denote them as being mentally ill, and I never see the things that these individuals say are there in the room. They are images being projected by their own minds - they are not things that are really there, on any level, including the physical, etheric, or astral.
Because mainstream medicine has no grasping of psychic phenomena, an innocent patient who is psychic may end up being labelled a schizophrenic. Imagine growing up in a haunted house like I did, where doors would slam, there would be creepy footsteps down the hall at night, scratches in the ceiling, and a feeling of being watched even though you are alone; now imagine taking that info to say, an MD, or a psychiatrist. Because they are totally based on empirical data, and there is no modern proof of these paranormal things, they are more likely to deem you insane. I never had to do this though, because my entire family, and friends who would sleep over, would all comment on the same things.
Secret agencies like the CIA and MI5 are fully aware of psychic phenomena. They employ psychics to do things like remote viewing on a regular basis, or to be present during interrogations. Psychics are never 100% accurate but they have a much higher accuracy rate than the average person, and they can usually read people like a book. However, the government still denies that such things are real.
If you want to see real research about this stuff you need to consult Russian sources. The mainstream of western science has been heavily influenced by the social pressures of religion, but the Russian sources have not.
