The impact of initiation: Early onset marijuana smokers demonstrate altered Stroop performance and brain activation.
Kelly A. Sagar, M K Dahlgren, A Gönenç, M T Racine, M W Dreman, Staci A Gruber
Developmental Cognitive Neuroscience December 2015 DOI: 10.1016/j.dcn.2015.03.003 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Peer reviewed |
|---|---|
| Sample size | 84 |
| Population | 50 chronic marijuana smokers (24 early onset, 26 late onset) and 34 healthy control participants |
| Measures | Stroop Color Word Test (Interference subtest), fMRI |
| Topics | Cannabis |
| Keywords | Age of onset Cognition Executive function Stroop FMRI |
| Key findings | Chronic marijuana smokers showed poorer Stroop Interference performance and altered cingulate cortex activation compared with healthy controls. Early-onset smokers (regular use before age 16) performed significantly worse than both controls and late-onset smokers, and earlier onset plus greater frequency and amount of use predicted poorer performance. The authors contend these results underscore the importance of age of onset and patterns of marijuana use and support education and intervention efforts among youth. |
Abstract
Marijuana (MJ) use is on the rise, particularly among teens and emerging adults. This poses serious public health concern, given the potential deleterious effects of MJ on the developing brain. We examined 50 chronic MJ smokers divided into early onset (regular MJ use prior to age 16; n=24) and late onset (age 16 or later; n=26), and 34 healthy control participants (HCs). All completed a modified Stroop Color Word Test during fMRI. Results demonstrated that MJ smokers exhibited significantly poorer performance on the Interference subtest of the Stroop, as well as altered patterns of activation in the cingulate cortex relative to HCs. Further, early onset MJ smokers exhibited significantly poorer performance relative to both HCs and late onset smokers. Additionally, earlier age of MJ onset as well as increased frequency and magnitude (grams/week) of MJ use were predictive of poorer Stroop performance. fMRI results revealed that while late onset smokers demonstrated a more similar pattern of activation to the control group, a different pattern was evident in the early onset group. These findings underscore the importance of assessing age of onset and patterns of MJ use and support the need for widespread education and intervention efforts among youth.
Comparable studies
Other observational and cohort studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population | 2009 | Case-control study | n = 454 |
| Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population | 2013 | Observational study | |
| Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people | 2000 | Observational | |
| Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline | 2011 | Observational cohort | n = 1,923 |
| Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... | 2005 | Observational cohort | n = 535 |
Citations in the library
Cited by 14
- Verbal Memory Performance and Reduced Cortical Thickness of Brain Regions Along the Uncinate Fasciculus in Young Adult Cannabis Users Cannabis and Cannabinoid Research March 29, 2018
- Altered Functional Connectivity Dynamics Serving Cognitive Flexibility in Regular Cannabis Users. Addiction Biology February 1, 2025
- Network topology and cannabis use following two weeks of monitored abstinence: moderation of sex and patterns of use findings. Frontiers in adolescent medicine 2025
- Altered functional connectivity and oscillatory dynamics in polysubstance and cannabis only users during visuospatial processing. Psychopharmacology April 2023
- Systematic review of structural and functional neuroimaging studies of cannabis use in adolescence and emerging adulthood: evidence from 90 studies and 9441 participants. Neuropsychopharmacology April 2022
and 9 more in the library
Cites 11
- Cannabis use before age 15 and subsequent executive functioning The British Journal of Psychiatry May 31, 2011
- Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings Current Pharmaceutical Design May 10, 2014
- Long-term effects of marijuana use on the brain. Proceedings of the National Academy of Sciences November 25, 2014
- Cannabis use and neurocognitive functioning in a non-clinical sample of users Addictive Behaviors February 6, 2014
- Why so impulsive? White matter alterations are associated with impulsivity in chronic marijuana smokers. Experimental and Clinical Psychopharmacology June 2011
and 6 more in the library