Background:
Structural magnetic resonance
imaging techniques are powerful tools for examining the effects of drug use on
the brain. The nicotine and cannabis literature has demonstrated differences
between nicotine cigarette smokers and cannabis users compared to controls in
brain structure; however, less is known about the effects of co-occurring
cannabis and tobacco use.
Methods:
We used voxel-based
morphometry to examine gray matter volume differences between four groups: (1)
cannabis-dependent individuals who do not smoke tobacco (Cs); (2)
cannabis-dependent individuals who smoke tobacco (CTs); (3) cannabis-naïve,
nicotine-dependent individuals who smoke tobacco (Ts); and (4) healthy controls
(HCs). We also explored associations between gray matter volume and measures of
cannabis and tobacco use.
Results:
A significant group
effect was observed in the left putamen, thalamus, right precentral gyrus, and
left cerebellum. Compared to HCs, the Cs, CTs, and Ts exhibited larger gray
matter volumes in the left putamen. Cs also had larger gray matter volume than HCs
in the right precentral gyrus. Cs and CTs exhibited smaller gray matter volume
than HCs in the thalamus, and CTs and Ts had smaller left cerebellar gray
matter volume than HCs.
Conclusions:
This study extends
previous research that independently examined the effects of cannabis or
tobacco use on brain structure by including an examination of co-occurring
cannabis and tobacco use, and provides evidence that cannabis and tobacco
exposure are associated with alterations in brain regions associated with addiction.
Below: Group differences in gray
matter volume. Clusters of significant volume differences (p <
0.001, famiy-wise error (FWE) cluster-corrected at p <
0.05) are displayed on representative sagittal, coronal, and axial slices overlain
on the standard Montreal Neurological Institute brain. Right side of the brain
is depicted on the right side. C, cannabis-dependent individual who does not
smoke tobacco; CT, cannabis-dependent individual who smokes tobacco; HC,
healthy control; L, left; R, right; T, cannabis-naïve, nicotine-dependent
individual who smokes tobacco.
Full article at: http://goo.gl/KK4FnO
By: Reagan R. Wetherill, PhD, Kanchana Jagannathan, MS, Nathan Hager, BA, Anna Rose Childress, PhD, Hengyi Rao, PhD, and Teresa R. Franklin, PhD
University of
Pennsylvania, Department of Psychiatry, Philadelphia, PA (Drs Wetherill,
Jagannathan, Childress, Rao, and Franklin, and Mr Hager).
Corresponding
author.
Correspondence: Reagan R. Wetherill, PhD, University of
Pennsylvania, Department of Psychiatry, 3900 Chestnut Street, Philadelphia, PA
19104 (Email: ude.nnepu.dem.liam@htewr).
More at: https://twitter.com/hiv_insight
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