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Herb, asparagus, ganja — call it what you will — marijuana has long been a highly sought-after vice for many people. In fact, the latest federal survey on drug use indicated that approximately 24 million U.S. adults are current marijuana users — and that number is only expected to climb.

With cannabis use on the rise and more states legalizing the drug either medicinally or recreationally, lawmakers are puzzling over the question of how to determine if someone is impaired by marijuana.

Researchers at the University of Chicago are looking to unlikely technology for the answer: an app.

They’re in the midst of developing a prototype app called “Am I Stoned” in the hopes of creating a framework that would properly detect impairment from marijuana use.

“Stoned” app vs. breathalyzer

Harriet de Wit, PhD, a professor in the Department of Psychiatry and Behavioral Neuroscience at the University of Chicago who is leading up the research, noted that the app aims to improve the safety of marijuana use while contributing to the scientific knowledge of how marijuana physically and psychologically affects people.

De Wit presented the findings of a study on the app’s effectiveness at the American Society for Pharmacology and Experimental Therapeutics’ annual meeting today during the 2018 Experimental Biology meeting.

De Wit and her team asked 24 healthy non-cannabis users to consume either a placebo or 7.5 or 15 milligrams of THC. The participants, who didn’t know whether they consumed the placebo or the drug, then completed an assortment of computer-based tasks and app-based tasks on an iPhone to test impairment and measure functioning skills like critical tracking, memory, and time perception.

Using computer and app-based tasks, the researchers were successfully able to detect impairments caused by THC. The study ultimately showed that upon completing the tasks, users were more aware of their impairment levels.

However, the app — which has only been tested in a laboratory setting — still needs more work before it can be deployed in the real world and used to determine if someone is too high to drive.

Three or four of the computer tasks, which took about 15 to 20 minutes to complete, effectively detected impairment while just one of the iPhone tasks was able to identify impairment.

According to Elisa Pabon, a doctoral student at the University of Chicago who is helping lead the study, highly sensitive tasks are needed to effectively detect impairments, as the effects of cannabis tend to be subtle. Because the computer tasks took longer to complete, they may have been better equipped to evaluate these subtleties.

Why we don’t have a good test yet

The study comes after a long history of unreliable and ineffective methods of testing for tetrahydrocannabinol (THC) impairments. THC is the main ingredient in marijuana that causes a person to become high.

Currently, we don’t have the equivalent of an alcohol breathalyzer test to determine the effect that cannabis is having on the user’s brain — something that’s greatly needed for roadside testing.

“This study, and other controlled laboratory studies like it, is an important first step in this process that shows the potential for mobile tasks for these purposes, as well as the importance of validating such tasks against other established tests,” Nehal P. Vadhan, PhD, an assistant investigator at the Center for Addiction Services and Personalized Interventions at the Feinstein Institute for Medical Research, told Healthline.

Because while urine and blood testing can measure recent drug use, they alone cannot test and detect impairment levels. Up until now, interpreting areas of performance and impairment — such as attention, perception, and coordination — has been largely subjective.

It’s not a question of if marijuana affects mental function and performance — it’s a question of how much.

So far, research has been hazy in determining how much marijuana use increases the risk of car accidents. Unlike alcohol, how much marijuana is in someone’s blood isn’t directly correlated with how high they are, and consequently, their driving abilities.

Depending on how you ingest marijuana — by smoking, vaping, or eating — the drug can have a different effect. For example, edibles and vaporization typically result in a more powerful and time-consuming high.

“There are also factors such as one’s tolerance levels, method of consumption, and whether marijuana is being used recreationally or medicinally that makes it difficult to compare one person to the next,” Evan Bronstein, CEO of Sawatch Hemp, a hemp production facility located in Colorado, told Healthline.

“There would also need to be a way to test users’ pre- and post-marijuana abilities to get a fair gauge of an individual’s impairment,” Bronstein added.

Alcohol is typically distributed, digested, and cleared out of the body within hours because ethanol, the chemical in alcoholic beverages, dissolves in water. Seeing that the body is mostly comprised of water — about 60 percent to be exact — it’s not difficult for our bodies to get rid of the ethanol.

However, the main ingredient in marijuana that makes people high is THC which dissolves in fat. It can stay in the body for days to weeks, long after intoxication has subsided. Because of this, unlike alcohol, blood and urine tests cannot truly tell us how marijuana is affecting the brain.

While researchers are looking for an answer, it will take much more investigation and study before a definitive marijuana intoxication test can be developed and widely used.

“In addition to improving their sensitivity, future steps would include accounting for issues like performance motivation, the effects of repeated task exposure, and task performance’s relationship to clinically-relevant behaviors like driving,” Vadhan said.

While the results of this early study were mixed, the researchers from the University of Chicago plan to use their findings to improve the sensitivity of the app-based tasks so eventually people can figure out just how high they are.