Researchers report brain-based approach to determining marijuana intoxication damage

Researchers at Massachusetts General Hospital (MGH) have found that a non-invasive brain imaging procedure is an objectively reliable way to identify those whose performance is impaired by THC, the psychoactive component in marijuana.
individual
.

The technique uses an imaging technique called functional near-infrared spectroscopy (fNIRS) to measure brain activation patterns associated with THC poisoning damage

With the increase in legalized marijuana use, there is an urgent need for a portable brain imaging procedure that can differentiate between THC impairment and mild intoxication
.

"Our study represents a new direction in impairment testing in the field," said lead author Dr.

In past studies, THC has been shown to impair cognitive and psychomotor performance critical 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 human body does not correspond well with dysfunction

In the MGH study, 169 marijuana users had near-infrared brain imaging before and after taking oral THC or a placebo
.

Compared with those who reported low or no intoxication, participants who reported intoxication after oral administration of THC showed increased concentrations of oxyhemoglobin (HbO) -- a signature of neural activity from the prefrontal cortex of the brain

"Identifying acute injury from THC poisoning through portable brain imaging may be an important tool in the hands of police officers in the field," explained senior author and principal investigator A.
Eden Evins, MD, MPH, adult Founding Director of the Center for Addiction Medicine
.

"Injuries identified by the machine learning model using only information from fNIRS matched self-reported and clinically assessed injuries 76% of the time, confirming the accuracy of the method

While this study did not specifically evaluate the use of NIR spectroscopy for roadside assessment of impaired driving, it does cite considerable advantages for this application
.

These include the feasibility of an inexpensive, lightweight, battery-operated near-infrared spectrometer device that could store data on wearables or wirelessly transmit data to a laptop

"Some companies are developing an alcohol-measuring device that only measures people's exposure to marijuana, not the damage marijuana causes," Gilman said
.

"We need a method that neither penalizes medical marijuana users.

Gilman is an associate professor of psychiatry at Harvard Medical School
.

Evans is the Cox Family Professor of Psychiatry at Harvard Medical School

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