By Meryem Yucel

Cannabis is the most frequently detected illicit drug in drivers, and can double the risk of motor vehicle accidents. Currently, cannabis testing can determine whether an individual has used cannabis recently (e.g. in the past month), but cannot detect whether a person is acutely intoxicated or impaired. Thus, it is essential to develop novel methods to detect acute cannabis impairment, applicable in the real world, including roadside settings.

Jodi Gilman, Assistant Professor at Harvard Medical School and Massachusetts General’s Center for Addiction Medicine, and her team are trying to fill this important gap by discovering a brain-based method of detecting impairment.  Their work has recently been highlighted by STAT News (https://www.statnews.com/2018/01/09/marijuana-sobriety-test/). The group is currently testing the utility of fNIRS to objectively measure an individual’s acute impairment due to cannabis. As Gilman pointed out in the article, it is critical to avoid false positives in which an individual can look impaired because of factors other than cannabis—such as sleep deprivation or a medication the driver is taking.

Another problem the researchers need to overcome is the lack of each individual driver’s baseline brain activity, which was recently pointed out by Heather Bortfeld, a University of California, Merced, psychologist, and a member of the board of directors of our society. It is possible that cannabis itself changes the temporal dynamics of the brain response, which can potentially identify acute impairment without the need of a baseline measurement.

We will be following the updates of this impactful work as a community in the future.