Diffusion abnormalities in adolescents and young adults with a history of heavy cannabis use

Manzar Ashtari, Kelly Cervellione, John Cottone, Babak A. Ardekani, Sanjiv Kumra

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127 Scopus citations


Background: There is growing evidence that adolescence is a key period for neuronal maturation. Despite the high prevalence of marijuana use among adolescents and young adults in the United States and internationally, very little is known about its impact on the developing brain. Based on neuroimaging literature on normal brain developmental during adolescence, we hypothesized that individuals with heavy cannabis use (HCU) would have brain structure abnormalities in similar brain regions that undergo development during late adolescence, particularly the fronto-temporal connection. Method: Fourteen young adult males in residential treatment for cannabis dependence and 14 age-matched healthy male control subjects were recruited. Patients had a history of HCU throughout adolescence; 5 had concurrent alcohol abuse. Subjects underwent structural and diffusion tensor magnetic resonance imaging. White matter integrity was compared between subject groups using voxelwise and fiber tractography analysis. Results: Voxelwise and tractography analyses revealed that adolescents with HCU had reduced fractional anisotropy, increased radial diffusivity, and increased trace in the homologous areas known to be involved in ongoing development during late adolescence, particularly in the fronto-temporal connection via arcuate fasciculus. Conclusions: Our results support the hypothesis that heavy cannabis use during adolescence may affect the trajectory of normal brain maturation. Due to concurrent alcohol consumption in five HCU subjects, conclusions from this study should be considered preliminary, as the DTI findings reported here may be reflective of the combination of alcohol and marijuana use. Further research in larger samples, longitudinal in nature, and controlling for alcohol consumption is needed to better understand the pathophysiology of the effect of cannabis on the developing brain.

Original languageEnglish (US)
Pages (from-to)189-204
Number of pages16
JournalJournal of Psychiatric Research
Issue number3
StatePublished - Jan 2009

Bibliographical note

Funding Information:
Funding for this study was provided by NIMH Grant MH – 070612; the NIMH (Dr. Ashtari), 1RO1-MH073150-01A2 (Dr. Kumra) and 7K23MH64556-06 (Dr. Kumra). NIMH had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.


  • Adolescent
  • Brain
  • Cannabis
  • Diffusion tensor imaging
  • Magnetic resonance imaging
  • Tractography


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