Exploring the relationship between microdosing, personality and emotional insight: A prospective study

Microdosing — the regular ingestion of sub-perceptual doses of classic psychedelics such as LSD or psilocybin — has become culturally prominent amid claims of benefits to mood, creativity and performance. Biological action of these substances partly involves agonism at 5-HT2A receptors, while typical microdose ranges are described as roughly 1/20 to 1/10 of a recreational dose and are intended to avoid perceptual alterations. Empirical research to date is limited and mixed: some controlled studies report subtle acute effects or dose-thresholds for subjective effects, while naturalistic and prospective studies have found improvements in self-reported wellbeing but also increases in negative emotion or trait neuroticism in some samples. Personality traits and emotional awareness (alexithymia) have not been conclusively characterised in relation to microdosing, and existing prospective work has yielded inconsistent findings. Dressler and colleagues set out to examine whether a short course of naturalistic microdosing is associated with changes in five-factor personality traits and with emotional insight. The study posed four explicit research questions: whether microdosing leads to changes in self-reported personality traits; whether prior microdosing experience relates to personality; whether alexithymia and neuroticism are associated among people who microdose; and whether baseline alexithymia predicts subsequent increases in neuroticism. The investigators emphasised a prospective within-subject design with a minimum 31-day interval between assessments to capture short-term changes while permitting multiple dosing sessions between time points.

A prospective within-subject design was employed with two online assessments separated by at least 31 days. Baseline (T1) measures were taken between October 2019 and April 2020, and follow-up (T2) invitations were issued by e-mail 31 days after T1, with a single reminder sent 14 days later for non-responders. Ethical approval was obtained from the Georg-Elias-Müller-Institute of Psychology ethics committee. Participants were recruited globally via webpages, newsletters and social media of non-profit psychedelic organisations and online forums. Inclusion criteria were age 18+, English fluency, and past/current microdosing experience; exclusions included current mental health or neurological diagnoses, current substance use disorder, or history of psychosis. From 90 complete T1 responses, exclusions for non-current microdosers, non-psychedelic substances, recreational dosing, very high non-psychedelic drug use, or new antidepressant medication reduced the analysed sample to 76 at T1 and 24 with complete data at both T1 and T2. The final T1 sample ranged in age 18–68 (mean 33.0, SD 13.1), was 80.3% male, and participants reported residence across North America, Europe, Australia/New Zealand and other regions. Data collection used Qualtrics; participants provided an anonymous e-mail address and completed the Modified ASSIST substance use screener, the M5-50 personality questionnaire (extraversion, agreeableness, conscientiousness, neuroticism, openness), and the 20-item Toronto Alexithymia Scale (TAS-20). An administrative error led to omission of TAS-20 Item 2 from all calculations. Self-reported microdosing behaviour (substance type, typical dose, motives) and demographics were also recorded. Participants received no incentive. Statistical analyses used an alpha of 0.05. To test change over time, paired two-tailed t-tests compared T1 and T2 mean personality scores (n=24 for these tests). Correlations between prior experience indicators (total lifetime doses; months since first microdose) and personality at T1 used Spearman's rho because experience variables were non-normally distributed. Pearson correlation examined the relationship between alexithymia and neuroticism at T1. Finally, linear regression tested whether baseline alexithymia predicted change in neuroticism (T2 minus T1).

Substance use and sample characteristics: During the study interval participants reported between 3 and 30 microdoses (mean 11.3, SD 7.53). At T1, 33 participants reported microdosing psilocybin (mean dose 0.367 g, SD 0.503) and 23 reported microdosing LSD (mean dose 15.3 mg, SD 6.27); additional participants reported other psychedelics or did not provide clear dose information. Primary motives were most commonly personal growth and self-medication, with smaller numbers citing increased productivity, curiosity or creativity. Personality change over time: In the within-subject sample with complete T1–T2 data (n=24), conscientiousness increased and neuroticism decreased over the minimum one-month interval. Specifically, conscientiousness showed a significant increase (t = −2.26, P = 0.034, Cohen's d = −0.460) and neuroticism showed a significant decrease (t = 3.26, P = 0.003, d = 0.666). No significant changes were observed for extraversion, agreeableness or openness in the paired t-tests. Relationships with prior microdosing experience: Using the full T1 sample (N = 76), months of prior microdosing experience correlated negatively with neuroticism (Spearman r = −0.237, P = 0.039). Extraversion correlated positively with months of prior experience (r = 0.228, P = 0.047) and with lifetime number of microdoses (r = 0.262, P = 0.022). Lifetime doses did not show a statistically significant correlation with neuroticism. Alexithymia and neuroticism: At baseline, alexithymia (TAS-20) and neuroticism were positively associated (Pearson r = 0.526, P < 0.001; N = 76), indicating higher alexithymia scores related to higher neuroticism. In a linear regression among completers (n = 24), baseline alexithymia did not significantly predict change in neuroticism across the study interval (P = 0.077, R2 = 0.135). The authors note data availability but the extracted text does not provide a direct link.

Dressler and colleagues interpreted the observed increase in conscientiousness and decrease in neuroticism after a short naturalistic course of microdosing as evidence that microdosing may influence otherwise relatively stable personality traits. The decrease in neuroticism contrasts with a prior prospective study that reported a small increase in neuroticism; the investigators suggest sample differences in prior microdosing experience could explain divergent results. Specifically, participants in the present study tended to have more prior microdosing exposure than those in the earlier study, and months of prior experience correlated negatively with neuroticism. The authors consider two non-exclusive explanations: longer-term microdosing might reduce neuroticism through improved emotional processing, or people who experience reductions in neuroticism may be more likely to continue microdosing (self-selection). The increase in conscientiousness was discussed in behavioural terms — participants may have experienced improved organisation, responsibility and task completion — and was aligned with anecdotal reports of reduced procrastination. No reliable change in openness was observed, and the authors suggest this may reflect self-selection, whereby people already high in openness are more likely to try microdosing. Extraversion showed positive correlations with prior microdosing experience, consistent with the possibility that extroverted individuals engage more in long-term microdosing. Regarding emotional insight, the strong positive cross-sectional association between alexithymia and neuroticism at baseline was consistent with prior literature linking lower emotional literacy to higher neuroticism. However, baseline alexithymia did not predict subsequent change in neuroticism in this sample, although the negative correlation between prior microdosing experience and neuroticism was interpreted as suggestive that experienced microdosers may be better at integrating emotional insights. The investigators acknowledged multiple limitations that constrain causal inference and generalisability. The study was naturalistic and uncontrolled: substances, doses and dosing schedules varied and there was no placebo or blinding. Recruitment was English-language and likely subject to sampling bias, potentially over-representing participants with positive experiences. Ethical exclusions of individuals with current mental health or substance use diagnoses limit applicability to clinical populations, and concurrent recreational drug use among many participants complicates attribution of effects to microdosing alone. The authors therefore recommend experimental placebo-controlled trials with standardised dosing and inclusion of psychedelic-naive participants as priorities for future research, and suggest further work to disentangle effects in clinical samples and to examine alexithymia's role.

The study concludes that a short naturalistic period of microdosing was associated with increased conscientiousness and decreased neuroticism in a sample of predominantly experienced microdosers. Prior microdosing experience correlated negatively with neuroticism and positively with extraversion, and baseline alexithymia was associated cross-sectionally with higher neuroticism but did not predict subsequent neuroticism change. The authors propose that future controlled trials should test whether personality trajectories differ between microdosing-naïve and experienced participants and should examine the role of alexithymia in samples that include people with current mental health diagnoses.