Psilocybin and Personality Change: Can Psychedelic Therapy Reshape Traits Linked to Addiction?

Title: Multidimensional Personality Changes Following Psilocybin-Assisted Therapy in Patients With Alcohol Use Disorder: Results From a Double-Blind, Placebo-Controlled Clinical Trial
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Summary

A new study in The American Journal of Psychiatry explored how psilocybin-assisted therapy (PAT) affects personality traits in individuals with alcohol use disorder (AUD). Previous research has linked AUD to heightened neuroticism and impulsiveness, traits associated with increased alcohol consumption and relapse risk. This study examined whether PAT could "normalize" personality traits in AUD patients, particularly by reducing neuroticism and impulsiveness, which are known to predict drinking behavior. Findings revealed that psilocybin significantly reduced neuroticism while increasing extraversion and openness compared to an active placebo. Notably, reductions in impulsiveness were associated with lower alcohol consumption post-treatment, suggesting that personality shifts may play a key role in AUD recovery.

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What was the goal?

The study sought to answer three key questions:

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1. Does psilocybin-assisted therapy lead to long-term personality changes in individuals with AUD?
2. Do these changes reflect a normalization of personality traits typically associated with alcohol dependence?
3. Are reductions in impulsiveness linked to lower alcohol consumption following treatment?

Given the strong relationship between personality traits and substance use, understanding whether PAT can shift personality could provide new insights into how psychedelic therapy supports addiction recovery.

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What happened in the study?

• 84 adults with AUD were randomized to receive either two doses of psilocybin (N=44) or an active placebo (diphenhydramine; N=40), alongside 12 weeks of psychotherapy.
• Personality traits were measured before treatment (week 0) and seven months post-treatment (week 36) using the NEO Personality Inventory, which assesses five major personality factors (neuroticism, extraversion, openness, agreeableness, and conscientiousness).
• Alcohol consumption was tracked using the Timeline Followback method at multiple time points.

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Key findings

Psilocybin led to significant personality shifts

• Neuroticism decreased significantly in the psilocybin group, driven by reductions in depression, impulsiveness, and vulnerability.
• Extraversion increased, particularly in the positive emotion facet.
• Openness increased, with the strongest effects on openness to feelings and fantasy.
• No significant changes were observed in conscientiousness or agreeableness.

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Reductions in impulsiveness were linked to drinking outcomes

• Across all participants, greater reductions in impulsiveness correlated with lower alcohol consumption post-treatment.
• This relationship was strongest among those who continued moderate or high-risk drinking before the first psilocybin session.

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Personality changes appeared to normalize AUD-related traits

• Compared to a normative sample of 1000 people, personality traits in psilocybin-treated participants moved closer to general population averages (Figure 1).
• However, openness remained elevated post-treatment, suggesting psychedelics may enhance this trait beyond typical levels.

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Why is this important?

Most AUD treatments focus on behavioral control, but this study suggests that addiction recovery may be linked to deeper personality transformations. If psilocybin-assisted therapy can shift traits like neuroticism and impulsiveness, it could offer a fundamentally different approach to treating addiction, one that targets underlying psychological patterns rather than just drinking behavior. Additionally, the link between impulsiveness and drinking outcomes highlights the potential of using personality measures to predict who will benefit most from PAT. If future studies confirm this connection, screening for high impulsiveness could help identify patients who might be particularly responsive to psychedelic therapy.

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Limitations

• Lack of long-term follow-up. The study measured personality changes only up to seven months post-treatment. Whether these changes persist beyond this period remains unclear.
• Self-reported data. Personality and alcohol consumption were measured through self-report surveys, which may introduce bias.
• Functional unblinding. Most participants correctly guessed whether they received psilocybin or placebo, which could have influenced responses.
• Highly selective sample. Participants were predominantly white, affluent, and open to psychedelics, which may limit generalizability to broader AUD populations.

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Conclusion

This study provides evidence that psilocybin-assisted therapy can induce long-lasting personality changes in individuals with AUD, particularly by reducing neuroticism and impulsiveness while increasing extraversion and openness. Given the strong link between impulsiveness and alcohol misuse, these findings suggest that personality shifts may play a critical role in addiction recovery. However, further research is needed to determine how long these personality changes persist, whether they predict long-term abstinence, and whether similar effects occur in more diverse AUD populations. If future studies confirm these effects, personality-targeted psychedelic interventions could become a novel approach to treating substance use disorders.