According to the Many Minds interpretation of quantum mechanics (https://en.wikipedia.org/wiki/Many-minds_interpretation), the distinction between worlds in the Many Worlds interpretation should be made at the level of the mind of an individual observer. I have read that, in this case, each observer's mental states would be realized in at least one universe. According to the Many Minds interpretation all that matters is the mind and its mental states
When I found about this interpretation I though it was interesting, although I know it has no empirical support yet. But then I thought of something strange that I think would happen if this interpretation was true and I do not know if my idea is correct.
The thing is: When we observe something (e.g. an apple), a set of neurons are activated and they form a mental state representing the observation of that apple. People with mental illnesses (such as schizophrenia) tend to visualize things that do not really exist (for example, if a patient visualizes a monster, the mental states that would correspond to the observation of that monster are activated. Even if the monster does not exist, the mental states corresponding to that observation are activated, and therefore, the patient would really believe that there is a monster in front of it, since that "observation" would be indistinguishable from an observation of an actual thing)
Therefore, if Many-Minds considers that the observer is fundamental and that mental states corresponding to different observations are realized in different universes, then, would a schizophrenic patient's hallucinations actually exist in different universes? I mean, if this interpretation considers that the different mental states corresponding to what we observe actually indicates what is real, then, if a person suffers hallucinations, wouldn't it meant that these "observations" of those illusions could exist in different universes? That when a schizophrenic patient "sees" a monster, that monster could actually exist in some universe (since it corresponds to a mental state of an "observation")?