Incident psychotic experiences following self-reported use of high-potency cannabis: results from a longitudinal cohort study

Lindsey A. Hines, J. Heron, Stanley Zammit

Research output: Contribution to journalArticlepeer-review


Background: High-potency cannabis has been associated with increased risk of psychosis, but a lack of prospective data hinders understanding of causality in this relationship.

Aims: Combine prospective report of cannabis use with retrospective report of potency to infer the potency of cannabis used in adolescence and explore whether use of cannabis, and the use of high-potency cannabis, in adolescence is associated with incident psychotic experiences.

Design: Population-based birth cohort study.

Setting: United Kingdom

Participants: N=5570 participants who reported on any cannabis use (yes/no) age 16 and 18 years, and N=1560 participants from this group who also retrospectively reported on cannabis potency.

Measurements: In questionnaires at ages 16 and 18 individuals self-reported lifetime cannabis use, and at age 24, participants reported the type of cannabis they most commonly used in the whole time since first using cannabis. Psychotic experiences were assessed at age 24 years using the semi-structured Psychosis-Like Symptom Interview, with incident defined as new-onset occurring between ages 19 and 24 years.

Findings: Results indicated use of high-potency cannabis at age 16 or 18 is associated with twice the likelihood of experiencing incident psychotic experiences from age 19-24 (Odds Ratio 2.15, 95% Confidence Intervals 1.13-4.06). There was less evidence for an effect of any cannabis use on incident psychotic experiences (Odds Ratio 1.45, 95% Confidence Intervals 0.94 - 2.12).

Conclusions: This work contributes to a growing body of evidence indicating that use of high-potency cannabis is associated with increased likelihood of psychotic experiences.
Original languageEnglish
Issue number6
Early online date13 May 2024
Publication statusE-pub ahead of print - 13 May 2024

Data Availability Statement

The informed consent obtained from ALSPAC participants does not allow for the data to be made freely available through any third party maintained public repository. However, data used for this Article can be made available on request to the ALSPAC Executive. The ALSPAC data management plan describes in detail the policy regarding data sharing, which is through a system of managed open access. Full instructions for applying for data access can be found here: The ALSPAC study website contains details of all the data that are available (


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