Something, of course, subjective, that makes me think in causality is that you can appreciate changes that are not present in other people with mental problems.

Something, of course, subjective, that makes me think in causality is that you can appreciate changes that are not present in other people with mental problems. Just to be clear, I'm talking about heavy users here, not occasional users. I don't think is a so strange prior to have. After all, heavy use of almost anything, have secondary effects. I understand, this is an observation, not an experiment. Anyway, as a follower of Bayes, I have updated my probabilities.