Why so impulsive? White matter alterations are associated with impulsivity in chronic marijuana smokers.
Staci A Gruber, Marisa M Silveri, Mary Kathryn Dahlgren, Deborah A Yurgelun-Todd
Experimental and Clinical Psychopharmacology June 2011 DOI: 10.1037/a0023034 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Case-control neuroimaging study Peer reviewed |
|---|---|
| Sample size | 30 |
| Population | 15 chronic heavy marijuana smokers and 15 nonsmoking control subjects |
| Measures | Fractional anisotropy (FA), trace, Barratt Impulsivity Scale (BIS) |
| Topics | Cannabis |
| Key findings | Chronic heavy marijuana smokers showed reduced left frontal fractional anisotropy and higher right genu trace compared with nonsmokers, and had higher Barratt Impulsivity Scale total and motor scores. Left frontal fractional anisotropy was positively correlated with impulsivity, and earlier age of marijuana use onset was associated with higher frontal fractional anisotropy and lower trace. The authors propose early use may reduce white matter integrity and increase impulsivity, potentially contributing to use initiation or inability to quit. |
Abstract
Difficulty monitoring and inhibiting impulsive behaviors has been reported in marijuana (MJ) smokers; neuroimaging studies, which examined frontal systems in chronic MJ smokers, have reported alterations during inhibitory tasks. Diffusion tensor imaging (DTI) provides a quantitative estimate of white matter integrity at the microstructural level. We applied DTI, clinical ratings, and impulsivity measures to explore the hypotheses that chronic, heavy MJ smokers would demonstrate alterations in white matter microstructure and a different association between white matter measures and impulsivity relative to nonsmoking control subjects (NS). Fractional anisotropy (FA), a measure of directional coherence, and trace, a measure of overall diffusivity, were calculated for 6 locations including bilateral frontal regions in 15 chronic MJ smokers and 15 NS. Subjects completed clinical rating scales, including the Barratt Impulsivity Scale (BIS). Analyses revealed significant reductions in left frontal FA in MJ smokers relative to NS and significantly higher levels of trace in the right genu. MJ smokers also had significantly higher BIS total and motor subscale scores relative to NS, which were positively correlated with left frontal FA values. Finally, age of onset of MJ use was positively correlated with frontal FA values and inversely related to trace. These data represent the first report of significant alterations in frontal white matter tracts associated with measures of impulsivity in chronic MJ smokers. Early MJ use may result in reduced FA and increased diffusivity, which may be associated with increased impulsivity, and ultimately contribute to the initiation of MJ use or the inability to discontinue use.
Comparable studies
Other experimental studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Smoked Cannabis' Psychomotor and Neurocognitive Effects in Occasional and Frequent Smokers Occasional (<2x/week) and frequent (≥4x/week) cannabis smokers | 2015 | Controlled within-subjects study | n = 25 |
| Dissociable effects of cannabis with and without cannabidiol on the human brain’s resting-state functional connectivity Healthy volunteers experienced with cannabis but not regular users | 2019 | Within-subjects experimental design | n = 17 |
| Which biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like effects? Young cannabis users | 2018 | Observational study (naturalistic, within-subject counterbalanced design) | n = 410 |
| Cannabis Essential Oil: A Preliminary Study for the Evaluation of the Brain Effects Healthy volunteers | 2018 | Experimental study | n = 5 |
| Coming off cannabis: a cognitive and magnetic resonance imaging study in patients with multiple sclerosis Patients with multiple sclerosis who began using cannabis after disease onset, used it... | 2019 | Quasi-experimental study with odd-even allocation | n = 40 |
Citations in the library
Cited by 16
- The neuropsychopharmacology of cannabis: A review of human imaging studies Pharmacology & Therapeutics October 20, 2018
- Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings Current Pharmaceutical Design May 10, 2014
- 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
- What Do Thirty Years of Neuroimaging Research Tell Us About Recreational Cannabis Use and Brain Integrity? A Narrative Review of the Multimodal Neuroimaging Evidence to Date. Substance Abuse and Rehabilitation 2026
- The Link Between Cannabis Use and Violent Behavior in the Early Phase of Psychosis: The Potential Role of Impulsivity Frontiers in Psychiatry March 22, 2022
and 11 more in the library
Cites 3
- Neural substrates of faulty decision-making in abstinent marijuana users. Neuroimage June 2005
- Neuroimaging of marijuana smokers during inhibitory processing: a pilot investigation. Brain research. Cognitive brain research April 2005
- Abnormal brain activity in prefrontal brain regions in abstinent marijuana users. Neuroimage November 2004