Brain-based method to determine impairment from cannabis intoxication
Traditional breathalyzer testing for alcohol impairment is unreliable in judging acute impairment from cannabis

Date:
January 11, 2022
Source:
Massachusetts General Hospital
Summary:
A new study shows that imaging of brain activity with functional
near- infrared spectroscopy might offer a more accurate and reliable
way to distinguish impairment from cannabis intoxication.



FULL STORY ========================================================================== Researchers at Massachusetts General Hospital (MGH) have found a
noninvasive brain imaging procedure to be an objective and reliable way
to identify individuals whose performance has been impaired by THC,
the psychoactive ingredient in cannabis. The technique uses imaging
technology known as functional near-infrared spectroscopy (fNIRS) to
measure brain activation patterns that correlate to impairment from THC intoxication. As reported in the journal Neuropsychopharmacology,the
procedure could havesignificant implications for improving highway and workplace safety.


==========================================================================
The increased use of cannabis through legalization has created the urgent
need for a portable brain imaging procedure that can distinguish between impairment and mild intoxication from THC. "Our research represents a
novel direction for impairment testing in the field," says lead author
Jodi Gilman, PhD, investigator in the Center for Addiction Medicine,
MGH. "Our goal was to determine if cannabis impairment could be
detected from activity of the brain on an individual level. This is a
critical issue because a 'breathalyzer' type of approach will not work
for detecting cannabis impairment, which makes it very difficult to
objectively assess impairment from THC during a traffic stop." THC has
been shown in past studies to impair cognitive and psychomotor performance essential to safe driving, a factor thought to at least double the risk
of fatal motor vehicle accidents. The challenge for scientists, however,
is that the concentration of THC in the body does not correspond well to functional impairment. One reason is that people who use cannabis often
can have high levels of THC in the body and not be impaired. Another is
that metabolites of THC can remain in the bloodstream for weeks after the
last cannabis use, well beyond the period of intoxication. Hence the need
for a different method to determine impairment from cannabis intoxication.

In the MGH study, 169 cannabis users underwent fNIRS brain imaging
before and after receiving either oral THC or a placebo. Participants
who reported intoxication after being given oral THC showed an increased oxygenated hemoglobin concentration (HbO) -- a type of neural activity signature from the prefrontal cortex region of the brain -- compared to
those who reported low or no intoxication.

"Identification of acute impairment from THC intoxication through portable brain imaging could be a vital tool in the hands of police officers in the field," explains senior author and principal investigator A. Eden Evins,
MD, MPH, founding director of the Center for Addiction Medicine. "The
accuracy of this method was confirmed by the fact impairment determined
by machine learning models using only information from fNIRS matched self-report and clinical assessment of impairment 76 percent of the time." While the study did not specifically assess fNIRS in roadside assessments
of impaired driving, it did cite considerable advantages for such an application.

These include the feasibility of inexpensive, lightweight, battery-powered fNIRS devices that allow data to either be stored on wearable recording
units or transmitted wirelessly to a laptop. Moreover, fNIRS technology
could be incorporated into a headband or cap, and thus require minimal
set-up time.

"Companies are developing breathalyzer devices that only measure exposure
to cannabis but not impairment from cannabis," says Gilman. "We need
a method that won't penalize medical marijuana users or others with insufficient amounts of cannabis in their system to impair their
performance. While it requires further study, we believe brain-based
testing could provide an objective, practical and much needed solution."
Gilman is associate professor of Psychiatry at Harvard Medical
School. Evins is the Cox Family Professor of Psychiatry at Harvard
Medical School.

The study was funded by the National Institute on Drug Abuse.

special promotion Explore the latest scientific research on sleep and
dreams in this free online course from New Scientist -- Sign_up_now_>>> academy.newscientist.com/courses/science-of-sleep-and-dreams ========================================================================== Story Source: Materials provided by Massachusetts_General_Hospital. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jodi M. Gilman, William A. Schmitt, Kevin Potter, Brian Kendzior,
Gladys
N. Pachas, Sarah Hickey, Meena Makary, Marilyn A. Huestis,
A. Eden Evins.

Identification of ∆9-tetrahydrocannabinol (THC) impairment
using functional brain imaging. Neuropsychopharmacology, 2022;
DOI: 10.1038/ s41386-021-01259-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220111153605.htm

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