17 Sep Cannabis Users Have Increased Neural Activity, Even at Rest
MedicalResearch.com Interview with:
Dr. Francesca M. Filbey PhD
Program Head, Cognition and Neuroscience PhD
Bert Moore Chair in BrainHealth
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The cannabis literature has generally focused on changes in brain function when engaged in a task. We were interested in examining whether these differences are present when not engaged in a task (i.e., during resting state) to understand baseline functional organization of the brain. Changes to baseline functional organization may reflect changes in brain networks underlying cognition. We also wanted to investigate whether specific brain waves, as measured by electroencephalography (EEG), are associated with measures of cannabis use, such as craving.
MedicalResearch.com: What should readers take away from your report?
Response: We measured neural activity using EEG from the cortex of the brain and found that individuals who use cannabis have increased neural activity, even when not engaged in a task. This activity is typically task-related and is reduced during resting state. We also found that measures of neural connectivity were associated with craving and cannabis use. Based on the previous literature, this finding suggests that there is reduced neural efficiency and increased cortical “noise” related to cannabis use. This difference in neural activity may be related to the cognitive impairments that other studies have reported in cannabis users.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: As is standard in our studies, we required participants to be abstinent from cannabis for 24 hours to avoid acute intoxication during the session. Thus, it is unclear whether our results reflect ongoing cannabis use or this short-term abstinence. We did collect information on time since last use, which ranged up to 60 hours, and found no associations with neural activity. This indicated that the effects were likely related to the ongoing cannabis use, but this should be verified. It would also be beneficial to examine differences in individuals with cannabis use disorder, as most of our sample did not meet the criteria, despite being almost daily users.
MedicalResearch.com: Is there anything else you would like to add?
Response: It is important to replicate and extend these findings. The neural associations we found may reflect general neural signatures of substance use as well as those that are specific to cannabis. These findings are a promising step towards developing electrophysiological neural correlates using EEG. As EEG is non-invasive and cost-effective, it is a potentially valuable tool for tracking and evaluating intervention strategies for substance abuse.
Shikha Prashad, Elizabeth S. Dedrick, Francesca M. Filbey. Cannabis users exhibit increased cortical activation during resting state compared to non-users. NeuroImage, 2018; 179: 176 DOI: 10.1016/j.neuroimage.2018.06.031
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