The link between cannabis use and cognitive functioning has captivated scientists and the public. In this section, we present our original study followed by a commentary on the study, some letters to the editor, and two subsequent studies. In addition, we provide links to media coverage, most of which is serious and some of which is funny. Collectively, these readings lay out some of the concerns and controversies in this area of research. These readings can be packaged together for teaching purposes.

Original article

Meier MH, Caspi A, Ambler A, Harrington HL, Houts R, Keefe RSE, McDonald K, Ward A, Poulton R, Moffitt TE
Persistent cannabis users show neuropsychological decline from childhood to midlife
2012 Proceedings of the National Academy of Sciences Plus 109:2657-2664


Gonzalez R. Swanson JM.
(2012) Long term effects of adolescent onset and persistent use of cannabis. PNAS 109: 5970–15971,–15971

Letters to the Editor

Rogeberg O (2013) Correlations between cannabis use and IQ change in the Dunedin cohort are consistent with confounding from socioeconomic status. PNAS, 110:4251-4254.

Daly M (2013) Personality may explain the association between cannabis use and neuropsychological impairment. PNAS, 110:E979

Moffitt TE, Meier MH, Poulton R, Caspi A. (2013). Reply to Rogeberg and Daly: No evidence that socioeconomic status or personality differences confound the association between cannabis use and IQ decline. PNAS, 110:E980-2

Here are subsequent, independent reports about the link between cannabis use and neuropsychological decline.

It is instructive to read Meier et al. alongside these articles, and to compare and contrast the approaches and conclusions

Meier et al. (2017). Associations between adolescent cannabis use and neuropsychological decline: a longitudinal co-twin control study. Addiction, 113:257-265.

Jackson NJ et al. (2016). Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies. PNAS, 113: E500-508.

Auer R et al. (2016). Association Between Lifetime Marijuana Use and Cognitive Function in Middle Age: The Coronary Artery Risk Development in Young Adults (CARDIA) Study. JAMA: Internal Medicine, February 01, 2016. doi:10.1001/jamainternmed.2015.7841

Hall W. Lynskey M. (2016). Long-term Marijuana Use and Cognitive Impairment in Middle Age. JAMA: Internal Medicine, February 01, 2016. doi:10.1001/jamainternmed.2015.7850

Media coverage

Here are some interesting reactions to, and discussions about, our research into the link between cannabis and cognitive functioning.

Nature, Message from the Director of NIDA-Dr. Nora Volkow, Teen cannabis use lowers IQ, despite claims to the contrary, Interview with NIDA, Legalized Pot: Washington Post OpEd, Legalized Pot: NY Times OpEd,

Obvious finding of the year

Science of marijuana: NY Times OpEd

NIDA for teens

Reactions to AMA report recommending against legalization

NPR story on marijuana and the brain.

Does cannabis really lower your IQ?

Marijuana and impaired memory.

Washington Post reports on the various recent studies.

Just google 'cannabis' and 'IQ', and open your mind to the blogosphere. Or compare contrasting positions by visiting and

The Potency of Cannabis

Changes in cannabis potency over the last two decades (1995-2014)

2016 NIH marijuana and cannabinoid conference

This conference features many informative presentations. Madeline Meier also speaks about the cannabis-IQ link on Day 1, at 2 hours and 36 minutes.

March 22 (Day 1) video

March 23 (Day 2) video