In a large online survey of over 12,000 participants followed for two months, people who used psychedelics outside of medical supervision reported increases in psychotic and manic symptoms. These increases occurred only among those who used psychedelics in an illegal context. The severity of psychotic symptoms rose with more frequent use and more intense challenging experiences, while manic symptoms increased more in individuals with a history of schizophrenia or bipolar I disorder and those who reported a strong sense of insight during their psychedelic experience. The findings suggest that naturalistic psychedelic use in illegal settings may pose risks for certain individuals.
A 9-item scale called the Imperial Psychedelic Predictor Scale (IPPS) can predict key features of the acute psychedelic experience. The scale has three factors: set (mindset), rapport (relationship with the guide or setting), and intention. In a controlled administration dataset, set and rapport together explained 40% of the variance in mystical experiences, while set alone explained 16% of the variance in challenging experiences. In another controlled dataset, rapport explained 9% of the variance in emotional breakthrough. The scale shows good internal consistency and predicts mystical, challenging, and emotional breakthrough experiences across naturalistic and controlled settings.