The Bradford Hill Analysis of Causation Applied to Cannabis Use and the Development of Chronic Psychotic Disorders as appeared in the Appendix of the book, The Impact of THC on Our Children: A Parent’s Worst Nightmare.
Written by Christine L. Miller, PhD, Catherine Antley, MD, and Dean Whitlock (editor) with a review and contributions from Carsten Hjorthøj, PhD, Associate Professor, Copenhagen Research Center for Mental Health, University of Copenhagen
The Bradford Hill elements as set forth by van Reekum et al., 2001 for neuropsychiatric applications: van Reekum R, Streiner DL, Conn DK. “Applying Bradford Hill’s criteria for causation to neuropsychiatry: challenges and opportunities.” J Neuropsychiatry Clin Neurosci 13, no. 3 (Summer 2001): 318-25. https://doi.org/10.1176/jnp.13.3.318. PMID: 11514637. https://pubmed.ncbi.nlm.nih.gov/11514637.
A draft of this Bradford Hill analysis first appeared on IASIC1.org in June 2021.
Epidemiologist Austin Bradford Hill recognized that no one type of study could fully address the causal relationship between an agent and an outcome in human populations. The analysis he developed to categorize the different types of research necessary to substantiate causation has withstood the test of time.
Although not all key elements he defined can be applied to all types of outcomes, in the case of cannabis causing psychosis, their full application is possible. You will find in the attached what we will term “elements of causation” and the studies that satisfy them.
This is intended to be a living document, with edits from leading researchers incorporated as more relevant and up-to-date literature is made available. The sequential versions of the document will be archived for the record.
Updated June 4, 2021
Updated March 4, 2024