Prefrontal Cortex and Putamen Grey Matter Alterations in Cannabis and Tobacco Users

Yusuf Daniju, Paul Faulkner, Karen R. Brandt, Paul Allen

Research output: Contribution to journalArticlepeer-review


Background: Previous Magnetic Resonance Imaging (MRI) studies in regular cannabis users report altered grey matter volume (GMV) in brain regions, including the prefrontal cortex, putamen and hippocampus. However, most studies have tended to recruit recreational users with high levels of cannabis use, and have not controlled for the possible confounding effects of tobacco use. We attempt to address these limitations in the present study.
Methods: We acquired volumetric images in sex, age, and IQ matched groups of (1) regular Cannabis users who also smoke Tobacco cigarettes (‘CT=’; n =33), (2) non-cannabis-using Tobacco cigarette smokers (‘T’; n =19) and (3) non-cannabis/tobacco using Controls (‘C’; n =35). GMV in bilateral prefrontal cortex, putamen and hippocampal regions was compared across groups. We also examined associations between GMV differences and levels of cannabis and tobacco use, measures of intellectual function, and of depression, anxiety and stress.
Results: Relative to controls, both CT and T groups showed lower GMV in the left inferior frontal gyrus, and greater GMV in the putamen. Additionally, lower GMV in the right frontal pole in the CT group (but not the T group) was associated with lifetime cannabis use, but not cigarette use.
Conclusions: Regular cannabis users who also smoked tobacco cigarettes showed altered GMV patterns relative to controls. However, a similar pattern of GMV differences was also seen between regular tobacco users that did not use cannabis. Further research is needed to disentangle the effects of cannabis and tobacco use on brain structure.
Keywords: cannabis, tobacco, grey matter, prefrontal cortex, putamen.

Original languageEnglish
Publication statusPublished - 16 Sept 2022

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