Shamans are more like tour guides. Walking you through your own experience.
It is good to remember though that these approaches exist, and to let them be practiced safely and openly. As well as researched without interrupting it.
A tour guide does specific things. We could know what makes for a good or bad one.
Is a person who fakes the practice as good as a native life long taught shaman? Which kind of shaman is best? Is tailoring the experience needed and in what way? Etc.
That said, maybe it's more important to look at how these have been dealt with in the past than the data we have in the present.
The spike can just as well be caused by bad environment we made for ourselves, ecologically and psychologically.
The problem is, we really do not know what we're doing when dealing with mental issues. Typical western approach is only slightly better than dosing people with random psychedelic substances of mostly unknown effects. The science done in field of psychotherapy is low to non-existent quality. Methodologies are in their infancy.
Of course something barely effective will fail.
While I don't doubt there is some human component to this, what I worry about are interactions with standard prescriptions and OTC medicines.
Those risks are always weighted against benefits.
These are alpha-blockers for treating migraines or hypertension. There are psychotropic drugs based on these as well, and a bunch of discredited nootropics.
Now, high BDNF on its own is not a good or bad thing. It is released both when injuries and when growth happens...
I would be very careful recommending a shaman, unless you happen to have evidence for how well traditional approach to treatment works compared to recent drugs or current mental health treatments, or a precise description of what those people do, as it's more than just "take this drug and go home". We could use such studies for sure, and not for cultural appropriation!
We lack sufficient data to recommend for or against. (Partly because countries virtually banned research because "drugs" are "bad". Others are trying to hold it exclusive for their culture, which is wrong too. I think they should stand to gain from it if it works.)