Personality & Trait Factors

Personality and trait factors is not a condition or a treatment; it is a theme that runs through the whole field, and it points in two directions. The first is whether psychedelics change personality, the widely repeated idea that these experiences can durably alter stable traits, most famously by increasing "openness to experience". The second, quieter direction is whether personality predicts the response: whether traits a person already has shape how intense their experience is and whether they benefit.

The first question is the glamorous one, and it deserves scepticism precisely because it is so appealing. Personality is, almost by definition, the part of us that is stable over time, so "a single dose durably changed my personality" is an extraordinary claim that calls for strong evidence. The reality in the research is more cautious than the popular telling: the changes are generally modest, concentrated in people being treated for a condition, often not specific to the drug, and rarely demonstrated to last.

The single most important idea to carry through this page is the difference between feeling different and being different. Much of what looks like personality change is hard to separate from simply feeling better: when depression or anxiety lifts, scores on traits like neuroticism fall too, which may be symptom relief wearing the costume of trait change. The steadier, less heralded finding is that personality works as a predictor of the experience, which is a more defensible claim than the headline one. This page is distinct from the clinical personality disorders page, which covers personality as pathology rather than as a dimension that shifts.

Because there is no condition here, the relevant "standard practice" is how trait change is measured and how trustworthy those measurements are. The workhorse is the self-report Big Five questionnaire (openness, conscientiousness, extraversion, agreeableness, neuroticism), administered before and after. The best controlled evidence comes from layering these scales onto efficacy trials: a psilocybin trial for alcohol use disorder found reduced neuroticism and raised extraversion and openness against placebo[1]Am J Psychiatry (2025), psilocybin-AUD RCT (n=84): vs placebo, reduced neuroticism and increased extraversion and openness at week 36 (secondary analysis), which is a genuine, placebo-controlled signal. But the cleanest comparison is sobering: in a head-to-head against escitalopram, openness rose under both the psilocybin and the antidepressant, with no difference between them, and only neuroticism stayed reduced at six months[2]Psychol Med (2023), psilocybin vs escitalopram: openness rose under BOTH with no between-condition difference; only neuroticism and disagreeableness stayed down at 6 months.

Two measurement problems sit underneath all of this. First, short-window self-report struggles to distinguish a real trait shift from a lingering good mood, so a "personality change" measured weeks after a transformative experience may partly be state, not trait. Second, durability is rarely tested: most studies stop well before the months or years it would take to show a trait has genuinely, stably moved. The honest summary is that the measurement tools are adequate for symptoms but stretched when asked to prove that something as stable as personality has been rewritten, and the strongest single review across this literature is largely null[3]Neurosci Biobehav Rev (2024), meta-analysis (10 studies, 304 participants): no significant effects on the majority of personality, cognition and emotional-processing measures.

The more promising research direction is the less glamorous one: personality as a predictor rather than a product. Traits such as absorption and suggestibility appear to forecast the acute experience and even the response, and one trial found that pre-treatment suggestibility predicted response to psilocybin specifically[1]Psychol Med (2024), expectancy for psilocybin did NOT predict response; pre-treatment trait suggestibility predicted psilocybin (not escitalopram) response (n=55), while personality measurably shapes the sensory texture of the experience[2]Drug Alcohol Rev (2026), personality predicts the sensory effects of psychedelics (personality-as-predictor of the acute experience) and predicts features of the LSD state[3]Transl Psychiatry (2024), pharmacological and personality predictors of the LSD experience in healthy volunteers (meta-analysis). This is steadier ground than the trait-change claim, and potentially more useful, since predicting who will respond, or who will struggle, has real clinical value.

On the trait-change question itself, the most valuable work will be the kind that is currently missing: adequately powered trials with personality change as a primary outcome and genuinely long follow-up, designed to separate trait shift from symptom relief and from expectancy. The reframing in the alcohol study, which described its findings as a normalisation of abnormal personality expression in patients rather than generic enhancement[4]Am J Psychiatry (2025), psilocybin-AUD RCT (n=84): vs placebo, reduced neuroticism and increased extraversion and openness at week 36 (secondary analysis), points the honest way forward. The likely outcome is not the dramatic "psychedelics rewrite who you are" headline, but a narrower, more defensible claim: that in people who are unwell, easing the illness can shift some trait scores, mostly downward on neuroticism, in ways that may or may not prove durable.

The personality story has unusual cultural reach, which shapes who promotes it. The idea that a psychedelic can durably increase openness is attractive to the wellness and retreat industry (it promises lasting self-improvement), to researchers (it is a striking, publishable finding), and to users (it gives a transformative experience a measurable-sounding label). That alignment of incentives is exactly why the claim spreads faster than the evidence, and why a cross-sectional difference between users and non-users gets repeated as if it were proof of change. The same survey-based work that produces the eye-catching openness gap is, on inspection, mostly self-selection[1]Scientific Reports (2024), cross-sectional Swedish survey: users vs non-users differ on openness (d=1.72) — self-selection, not change (n=400 vs 400).

For an honest broker, this is a topic to deflate carefully rather than dismiss. There is a real, modest signal, especially reduced neuroticism in patients, and personality genuinely matters as a predictor of the experience. But "psychedelics change your personality" is an extraordinary claim resting on small samples, self-report scales, short follow-ups, non-specific effects and a founding study that does not even appear in much of the current evidence base. The responsible posture credits the modest, patient-centred findings, treats naturalistic "lasting personality change" reports as hypothesis-generating[2]Psyche (2026), naturalistic ayahuasca/Shipibo cohort: self-reported lasting changes in personality and quality of life (uncontrolled, traditional setting), and resists the slide from "people felt changed" to "their personality was durably altered", a slide the survey literature on perceived change[3]J Psychedelic Studies (2023), survey of perceived psychedelic personality change and its moderators (self-reported belief about change) shows is very easy to make.