Boys Town Researchers Find that Cannabis Changes how the Brain Responds to Threats
Friday, November 8, 2019
Cannabis use is becoming increasingly acceptable in the United States with several states legalizing cannabis for medical uses, and some states moving to decriminalization of recreational usage. However, increased access to cannabis is also creating potential harms, especially for adolescents whose brains are still developing.
James Blair, Ph.D., Susan and George Haddix Endowed Chair in Neurobehavioral Research, and his research team at Boys Town National Research Hospital are interested in how cannabis and alcohol use affects neurodevelopment. They recently published a study where they measured brain activity in 43 male and 44 female adolescents, ages 14–18, who volunteered for the study.
The researchers specifically looked at how the brain responds to threatening stimuli in young people with different levels of alcohol use disorder (AUD) or cannabis use disorder (CUD) symptoms . The teens saw threatening (angry faces, predatory animals) or neutral images. These appeared to loom towards (or recede from) the adolescents who were lying in a magnetic resonance imaging (MRI) scanner. This scanner detects brain activity through localized changes in blood flow.
Dr. Blair’s team found that more severe CUD, but not AUD, symptoms were related to less responding to looming threats within brain structures such as the rostral frontal cortex and the amygdala. These are brain regions critically involved in emotional processing.
The ability to respond to threats is important for guiding people away from dangerous or risky choices. In other work conducted previously by Dr. Blair’s team, reduced responding to threat on the same task has been related to an increased risk for aggression and antisocial behavior. The link between increased CUD and reduced threat processing may underpin some of the recent findings linking cannabis abuse to aggression. There remains a lot that we don’t know how cannabis and alcohol affect developing brains, and what changes may become long-term changes. For a more detailed review of these findings see the paper Threat Responsiveness as a Function of Cannabis and Alcohol Use Disorder Severity .
- Blair R.J.R., White S.F., Tyler P.M., Johnson K., et. al., (2019) Threat Responsiveness as a Function of Cannabis and Alcohol Use Disorder Severity. J Child Adolesc Psychopharmacol. 29(7):526–534.
- Coker-Appiah D.S., White S.F., Clanton R., Yang J., Martin A., Blair R.J. (2013) Looming animate and inanimate threats: The response of the amygdala and periaqueductal gray. Soc Neurosci 8:621–630.
About Boys Town National Research Hospital
Boys Town National Research Hospital offers a broad range of hospital and clinic services, backed by 40 years of life-changing research to provide the latest, most innovative care to our patients. The Hospital is internationally recognized as a leader in hearing research and clinical care and is leading research efforts in language and neuroscience to improve the lives of children and families across America.