Don't forget Ketamine. It's truly remarkable for depression and PTSD, arguably better than mdma or psilocybin because it's not as psychadelic but produces profound effects regardless. I took my mom to a ketamine clinic recently and up till then my biggest concern for her health was that she was always stuck in fight or flight, constant 11/10 stress levels, what I would call PTSD or complex PTSD. Anyway, after just 1 visit to ketamine clinic (2 low-medium dose sessions only), she's completely cured of her stress disorder. It's remarkable. This was a long-standing pattern for my mom and ketamine (with the help and guidance of an incredible therapist too) fixed it in a weekend, basically.
How does it actually work? Ketamine is a tranquilizer, right? Is it like a therapy session you do using Ketamine to turn off your stress so you can think clearly? How does it have lasting effects?
Basically how it worked was, during the session, my mom would lie down on a couch. I was there with her, therapist on a couch opposite her. She would have a blanket over her (she discovered on the trip also the amazing benefits of weighted blankets, which she now uses to great effect for helping her sleep too). Then the therapist would administer the ketamine via intramuscular injection, it would be a pre-agreed upon dosage based on feedback between you and the therapist. But then yeah, after the injection occurs, there's just some calm relaxing music playing, my mom has an eye cover on and she just lays back and rests. During the initial few minutes generally quite quiet, but she would also share a couple words here and there what she was feeling or seeing, but not really as a way to share more just that was part of her processing it. Generally the therapist and I would not say anything or interfere at all. While I do think my mom was able to kind of get a sense or feeling of / or better sense of proprotion of some psychological things going on inside of her, I suspect a lot of it is simply biochemical. Yes the talk therapy helped and the therapist was amazing, but it wasn't psychotherapy, it was very gentle and I guess helped my mom develop a better sense of proportion. A couple takeaways she had was how certain things weren't as important as others, for example.
I can't speak for GP, but when it's combined with talk therapy, the ketamine allows the body to lower its defenses so that talk therapy can more successfully be administered, and the combination of the two is what leads to long lasting effects, long after the ketamine has worn off. Ketamine let's the patient open up so talk therapy can get at the underlying issue and resolve that, in ways that talk therapy alone can't solve because the patient's flight /fight response/anxiety won't let them let their guard down to really talk about it.
Check out the other comments in this thread, i wrote a summary and someone else wrote a personal account. If you want to read more you could search on g scholar for a recent review paper on ketamine infusion therapy.
Ketamine has three distinct effects which are a function of dose. At medium doses it’s a recreational psychedelic and at large doses it’s an anaesthetic. Its highest efficacy against depression is seen in the micro-dose range, before any perceptual (psychedelic) effects start.
At that dose, it causes a rapid release of neurotrophic factors, which restores the function of neuronal spines. Those spines are typically damaged by chronic exposure to stress. It may not necessarily be supported by a verbal insight into your emotional difficulties, although the brief period of neuroplasticity can lead to that.
There is usually complete relief from depressive symptoms within 24-48h, but it only lasts for as long as chronic exposure to stress doesn’t start again. In some patients this means that symptoms can return within a couple of weeks, unfortunately.
In my experience, it fits the definition. On higher doses of MDMA I experience mild to moderate closed eye hallucinations when listening to music (morphing shapes). Though I have never had open-eyed hallucinations to any degree.
And I would absolutely define it as "consciousness expanding" in the sense that having conversations with friends while under its influence opens up aspects of my emotional mind that are very difficult for me to uncover while sober.
MDMA (ptsd), psilocybin (depression, anxiety), LSD
There are startups testing 2CB, DMT and some more exotic psychedelics for various indications as well.