Neuroimaging in cannabis use: a systematic review of the literature
R. Martín-Santos, Ana B. Fagundo, José Alexandre S. Crippa, Zerrin Atakan, Sagnik Bhattacharyya, Paul Allen, Paolo Fusar‐poli, Stefan Borgwardt, Marc L. Seal, Geraldo F. Busatto, Philip Mcguire
Psychological Medicine July 23, 2009 DOI: 10.1017/s0033291709990729 via OpenAlex
Summary
A systematic review of neuroimaging studies published up to January 2009 assessed evidence for cannabis effects on brain structure and function. Among 41 included studies, functional imaging indicated that resting global and prefrontal blood flow are lower in cannabis users than in controls. Activation studies during cognitive tasks produced inconsistent results. Acute administration of THC or marijuana increased resting activity and activation of the frontal and anterior cingulate cortex during cognitive tasks. Only three of eight structural imaging studies found differences between users and controls, providing minimal evidence of major effects of cannabis on brain structure.
Study at a glance
| Characteristics | Systematic review Peer reviewed |
|---|---|
| Topics | Cannabis |
| Keywords | Positron emission tomography Medicine Resting State FMRI Neuroscience |
| Citations | 207 |
| Key finding | Functional neuroimaging suggests modulation of global and prefrontal metabolism during rest and after THC/marijuana administration, but evidence for major structural brain changes from cannabis is minimal. |
Abstract
BACKGROUND: We conducted a systematic review to assess the evidence for specific effects of cannabis on brain structure and function. The review focuses on the cognitive changes associated with acute and chronic use of the drug. METHOD: We reviewed literature reporting neuroimaging studies of chronic or acute cannabis use published up until January 2009. The search was conducted using Medline, EMBASE, LILACS and PsycLIT indexing services using the following key words: cannabis, marijuana, delta-9-tetrahydrocannabinol, THC, cannabidiol, CBD, neuroimaging, brain imaging, computerized tomography, CT, magnetic resonance, MRI, single photon emission tomography, SPECT, functional magnetic resonance, fMRI, positron emission tomography, PET, diffusion tensor MRI, DTI-MRI, MRS and spectroscopy. RESULTS: Sixty-six studies were identified, of which 41 met the inclusion criteria. Thirty-three were functional (SPECT/PET/fMRI) and eight structural (volumetric/DTI) imaging studies. The high degree of heterogeneity across studies precluded a meta-analysis. The functional studies suggest that resting global and prefrontal blood flow are lower in cannabis users than in controls. The results from the activation studies using a cognitive task are inconsistent because of the heterogeneity of the methods used. Studies of acute administration of THC or marijuana report increased resting activity and activation of the frontal and anterior cingulate cortex during cognitive tasks. Only three of the structural imaging studies found differences between users and controls. CONCLUSIONS: Functional neuroimaging studies suggest a modulation of global and prefrontal metabolism both during the resting state and after the administration of THC/marijuana cigarettes. Minimal evidence of major effects of cannabis on brain structure has been reported.