I think the question can still be answered, one could, for example, explain how each drug can cause depression and state that they don't do it in comparable ways if that is the case
I understand how ADs cause depression when you stop taking them, but I don't understand how they can cause depression
while you are taking them (aside from building up a tolerance to their effects and having part of the original depression return). Like how they now come with warnings like "may cause suicidal ideation" etc. As far as I can tell from what I've read, it's not common for someone to be immediately
more depressed when they first begin taking ADs, but many people become depressed (even more depressed than they were before starting the AD) when they have been taking them for a long period of time, or when they stop taking them. The mechanism by which ADs can cause worsened depression when a person stops taking them has been studied and is fairly understood, but the way that an AD can cause depression while a person is taking it is not understood. The latter has been termed "Tardive Dysphoria". ADs can, ironically, actually cause permanent depression more severe than the original depression the person was being treated for.
A psychedelic like LSD on the other hand, can be a non-specific trigger for mental disorders, meaning that it is believed that the person would likely have developed the symptoms even if they didn't use LSD, something else would have triggered them. It's like the stress of the trip brought out a pre-existing mental illness (as many forms of stress can do). The most common adverse reaction to taking LSD is a "bad trip" - a temporary (less than 24 hours) episode of panic. Reactions that are prolonged and/or require treatment are usually termed "LSD psychosis". Most people to whom this happen have a history of psychiatric illness, took a very high dose and/or a lot of drugs over time, took the drug in a poor setting or may have been uncomfortable about using the drug to begin with. Of course there are exceptions; there have been occasional reports of severe/prolonged reactions occurring in people who seemed to have few mental health problems. And there are many people with mental health issues who use LSD without any adverse effects. However, just having depression isn't really considered a form of "LSD psychosis" and hasn't been studied as much.
Some healers who use psychedelics in therapy for mental health issues theorize that the psychedelic can bring the issues to the surface and force you to deal with them. They say one may experience a temporary "worsening" of symptoms, but if the drug is used in the right setting and with the right mindframe, the symptoms should fade and eventually you should feel better than before. I like this idea. It kind of makes sense to me because that when we, say, do a cleanse or make our diet healthier or start exercising more, we often feel worse temporarily. Why couldn't the same thing happen with the brain?
I don't think we know enough about how ADs or LSD can cause depression to determine whether they do it in a similar fashion, nor to determine that it isn't similar at all. But it seems to me that, like qwe said, the most likely explanation is that LSD or a bad trip can generally cause depression by being a psychologically stressful or traumatizing event, whereas ADs cause it by changing the way your brain functions (receptors/chemicals in the brain). However, this doesn't explain the person who has a pleasant LSD trip and then gets depressed in the following days.
There are also some similarities in what they do to the brain. LSD acts on serotonin receptors, dopamine receptors, and norepinephrine receptors. Most ADs increase the levels of serotonin, dopamine, and norepinephrine. So that is interesting.
Of course, it also depends if you are asking about ADs and LSD causing depression while you are on them, or after you stop taking them?
