Maybe also this: Single Dose of 'Magic Mushrooms' Hallucinogen May Create Lasting Personality Change

A single high dose of the hallucinogen psilocybin, the active ingredient in so-called "magic mushrooms," was enough to bring about a measurable personality change lasting at least a year in nearly 60 percent of the 51 participants in a new study, according to the Johns Hopkins researchers who conducted it.

From the abstract:

A large body of evidence, including longitudinal analyses of personality change, suggests that core personality traits are predominantly stable after age 30. To our knowledge, no study has demonstrated changes in personality in healthy adults after an experimentally manipulated discrete event. Intriguingly, double-blind controlled studies have shown that the classic hallucinogen psilocybin occasions personally and spiritually significant mystical experiences that predict long-term changes in behaviors, attitudes and values. (...) Consistent with participant claims of hallucinogen-occasioned increases in aesthetic appreciation, imagination, and creativity, we found significant increases in Openness following a high-dose psilocybin session. In participants who had mystical experiences during their psilocybin session, Openness remained significantly higher than baseline more than 1 year after the session.

Openness to experience:

Openness to experience correlates with creativity, as measured by tests of divergent thinking. Openness is also associated with crystallized intelligence, but not fluid intelligence. These mental abilities may come more easily when people are dispositionally curious and open to learning. However, openness is only weakly related to general intelligence. Openness to experience is related to need for cognition, a motivational tendency to think about ideas, scrutinize information, and enjoy solving puzzles.

Openness is the only personality trait that correlates with neuropsychological tests of dorsolateral prefrontal cortical function, supporting theoretical links among openness, cognitive functioning, and IQ.