The Afterglow Inventory (AGI): Validation of a new instrument for measuring subacute effects of classic serotonergic psychedelics
Tomislav Majić, Timo Torsten Schmidt, Anna Gröticke, Peter Gasser, Ricarda Evens, William A. Richards, Thomas Riemer
Journal of Psychopharmacology March 31, 2025 DOI: 10.1177/02698811251326937 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Cross-sectional survey Peer reviewed |
|---|---|
| Sample size | 1,480 |
| Population | Adults who had consumed a psychedelic or another non-psychedelic substance within the past 4 weeks |
| Topics | LSD Psilocybin Serotonin |
| Keywords | Afterglow Clinical psychology Hallucinogen Audiology |
| Citations | 4 |
| Key findings | The Afterglow Inventory (AGI) is a valid 24-item, 5-factor scale that quantifies positive subacute psychedelic afterglow effects and differentiates psychedelic users from controls. |
Abstract
Background: Classic psychedelics such as psilocybin and lysergic acid diethylamide are anecdotally associated with the phenomenon of “psychedelic afterglow,” a set of predominantly pleasant, temporary psychological effects reported after the acute effects have subsided. Since post-acute effects are crucial for the therapeutic use of psychedelics, an instrument to systematically assess subacute “afterglow” effects is needed.
Aims: To create and validate a questionnaire to quantify the subacute “afterglow” effects of psychedelics.
Methods: An international online survey was conducted in English and German. Participants who had consumed a psychedelic ( N = 1323) or another non-psychedelic substance (control group, N = 157) within the past 4 weeks were included. An initial list of 97 items was progressively reduced to 24 items.
Results: A 5-factor structure best fit the data and showed high internal consistency. The factors included (1) vitality, (2) transpersonal aspects, (3) inspiration/creativity, (4) interpersonal relationships, and (5) relationship to nature. The final 24-item version of the Afterglow Inventory (AGI) effectively differentiated between the psychedelic group and the control group. The overall AGI score positively correlated with the intensity ( r = 0.165; p < 0.001) and positive valence ( r = 0.251; p < 0.001) of the acute psychedelic effects.
Conclusions: The AGI is a novel scale for quantifying positive subacute (“afterglow”) effects of psychedelics. The use of the AGI could lead to a better understanding of the interplay between acute, subacute, and long-term effects of psychedelics. Insights could also be gained into how different substances, dosages, and extra-pharmacological factors, such as psychotherapy, might influence outcomes.
Comparable studies
Other cross-sectional and survey studies on serotonin, most cited first.
Citations in the library
Cited by 3
- Psychedelic-Related Psychosis: From Model Psychosis to Psychotherapy. Current Topics in Behavioral Neurosciences 2026
- Classifying Psychedelic-Related Complications Current Topics in Behavioral Neurosciences 2026
- Managing Psychological Challenges in the Subacute ("Afterglow") Window of Psychedelic Drug Effects. Current Topics in Behavioral Neurosciences 2026
Cites 52
- Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance Psychopharmacology July 7, 2006
- Trial of Psilocybin versus Escitalopram for Depression New England Journal of Medicine April 14, 2021
- Single-Dose Psilocybin for a Treatment-Resistant Episode of Major Depression. New England Journal of Medicine November 3, 2022
- Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later Journal of Psychopharmacology May 30, 2008
- Quality of Acute Psychedelic Experience Predicts Therapeutic Efficacy of Psilocybin for Treatment-Resistant Depression Frontiers in Pharmacology January 17, 2018
and 47 more in the library