Adult personality is thought to be essentially set by the age of 30. New research from Johns Hopkins University School of Medicine suggests that it may be more flexible. Nearly 60% of adults who were given a single high dose of the hallucinogen psilocybin experienced a measurable personality change, a strong increase in openness. This change lasted for over a year (the length of the study), and the researchers believe that it's likely to be permanent.

If these results are typical, psilocybin may have many therapeutic uses. The researchers are currently testing whether it can help cancer patients cope with the depression and anxiety that accompanies a diagnosis of cancer.

Psilocybin may not be an ideal therapeutic agent. But considering its ability to create personality changes once thought impossible, the researchers think it certainly deserves further study.

Openness is one of the five major personality traits — conscientiousness, extraversion, agreeableness, and neuroticism are the others (think OCEAN). Openness reflects a general appreciation for art, adventure, unusual ideas, imagination, curiosity and variety of experience. People who score low on openness tend to have more conventional interests, preferring the straightforward and obvious to the complex and subtle.

Normally, if openness changes at all as adults age, it tends to decrease.

Fifty-one psychologically healthy volunteers underwent two to five experimental sessions that lasted eight hours. At one of these sessions, they were given a moderate to high dose of psilocybin, though neither the subjects nor their monitors knew which session this would be.

During each session, participants were encouraged to lie down on a couch, use an eye mask to block external visual distraction, wear headphones through which music was played and focus their attention on their inner experiences. Two monitors were present at the subjects' side throughout the sessions.

Personality was assessed at the study's start, one to two months after each session and approximately 14 months after the last session.

No change was found in four of the five major personality traits: agreeableness, conscientiousness, extroversion and neuroticism. But significant increases in openness were found in 60% of the participants and persisted through the end of the 14-month study.

This isn't the first study to show that psilocybin can cause positive personality changes. A 2006 study also found positive changes in attitude, mood and behavior among adults who had taken psilocybin under controlled settings. But that study was more interested in a scientific analysis of mystical experiences. Psilocybin-containing mushrooms, often called magic mushrooms, have a long history of use in the religious ceremonies of natives of Central and South America that goes back to pre-Columbian times. The current study was specifically designed to monitor personality changes.

The researchers express several cautions about their findings. Nearly all the study subjects considered themselves spiritually active and over half had postgraduate degrees. It's not clear that similar results would be obtained for the general public. And some study participants reported strong fear or anxiety during their psilocybin sessions, though none reported any lingering harmful effects. This suggests that psilocybin may not be an ideal therapeutic agent. But considering its ability to create personality changes once thought impossible, the researchers think it certainly deserves further study.

The researchers also warn not to try this at home. Recreational psilocybin use doesn't always have a happy ending. And possession of psilocybin or psilocybin containing mushrooms is illegal in the U.S. and could lead to jail time.

An article on the Johns Hopkins study was published online September 28, 2011 by the Journal of Psychopharmacology and will also appear in a future print edition of the journal.