Erowid
 
 
Plants - Drugs Mind - Spirit Freedom - Law Arts - Culture Library  
Erowid References Database
Weiland BJ, Thayer RE, Depue BE, Sabbineni A, Bryan AD, Hutchison KE. 
“Daily marijuana use is not associated with brain morphometric measures in adolescents or adults”. 
J Neurosci. 2015 Jan 29;35(4):1505-12.
Abstract
Recent research has suggested that marijuana use is associated with volumetric and shape differences in subcortical structures, including the nucleus accumbens and amygdala, in a dose-dependent fashion. Replication of such results in well controlled studies is essential to clarify the effects of marijuana. To that end, this retrospective study examined brain morphology in a sample of adult daily marijuana users (n = 29) versus nonusers (n = 29) and a sample of adolescent daily users (n = 50) versus nonusers (n = 50). Groups were matched on a critical confounding variable, alcohol use, to a far greater degree than in previously published studies. We acquired high-resolution MRI scans, and investigated group differences in gray matter using voxel-based morphometry, surface-based morphometry, and shape analysis in structures suggested to be associated with marijuana use, as follows: the nucleus accumbens, amygdala, hippocampus, and cerebellum. No statistically significant differences were found between daily users and nonusers on volume or shape in the regions of interest. Effect sizes suggest that the failure to find differences was not due to a lack of statistical power, but rather was due to the lack of even a modest effect. In sum, the results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures.
Comments and Responses to this Article
#
earth
Feb 1, 2015 18:11
Media: New Study Finds Daily Marijuana Use Is Not Associated With Brain Abnormalities #

http://www.iflscience.com/brain/new-study-finds-daily-marijuana-use-not-associated-brain-changes

January 29, 2015 | by Justine Alford

Several recent studies have suggested that smoking marijuana is associated with physicalchanges in certain regions of the brain, both in terms of shape and volume, although they could not establish cause and effect. Now, new research which set out to replicate these investigations using a more robust experimental design has produced conflicting results. According to the study, daily marijuana use, in both adults and adolescents, is not associated with any significant differences in either the shape or volume of the regions investigated. The work has been published in The Journal of Neuroscience.
Submit Comment
[ Cite HTML ]