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Barely Buzzed or Super Stoned? An App Could One Day Reveal How High You Are
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How stoned are you, really?

That's the question researchers challenged marijuana users to answer in a prototype app called "Am I Stoned?" in which they completed a series of tasks evaluating their memory, cognitive speed, reaction time and fine-motor skills.

The prototype could in time make users more aware of the effects of THC (tetrahydrocannabinol), the compound in marijuana responsible for its psychoactive effects, the researchers said. This, in turn, may help them make safer choices about performing activities that may be difficult or dangerous to do while high, research team leader Harriet de Wit, a professor in the Department of Psychiatry and Behavioral Neuroscience at The University of Chicago, said in a statement.

The scientists presented their findings today (April 24) at the annual Experimental Biology conference; the results have not yet been published in a peer-reviewed journal. [25 Odd Facts About Marijuana]

When a person uses marijuana, THC interacts with the brain, stimulating dopamine production and creating a sense of euphoria. It also binds to cannabinoid receptors in brain regions associated with coordination, memory, cognition and time perception, and has been found to temporarily inhibit performance in these areas — though how much it does this depends on the individual and the amount and concentration of the THC consumed.  

To test the app, the scientists asked 24 people who didn't use marijuana daily to perform the app's tasks on iPhones and desktop computers after consuming either a pill containing THC or a placebo. Activities on the iPhone interface included a test of screen-tapping speed, a memory game of tapping flower images in the correct order, and a test that required shaking the phone in response to a blue dot appearing on the screen, to evaluate reaction time.

On the desktop, similar tasks addressed cognitive processing speed task, reaction time, fine motor coordination and working memory span, project researcher Elisa Pabon, a doctoral candidate at the Pritzker School of Medicine at The University of Chicago, told Live Science in an email.

The researchers found that the desktop interfaces could detect impairment successfully using three of the four tasks, while iPhone apps could do so with only one of the tasks. This is perhaps because the computer activities, which took 15 to 20 minutes to finish, offered more chances to observe how THC was affecting the user, Pabon said in the statement.

"The effects of THC on performance may be subtle, so we need highly sensitive tasks to detect impairments," Pabon said.

One drawback to a self-administered test such as this, however, is that if someone becomes good at performing the tasks through repetition and practice, the results won't accurately reflect how impaired they are, said Vaughan Rees, a lecturer on social and behavioral sciences at the Harvard T.H. Chan School of Public Health.

Rees, who was not involved in the app's development, also noted that vigilance and judgment planning — functions that could also be affected by THC — did not appear to be evaluated by the app, so its results could paint an incomplete picture of an individual's impairment.

At this stage, there is much more data that still needs to be gathered before the app can reliably test people for THC impairment, Pabon said. For example, it's important that the app factor in how a person performed on the tests when sober, and how repetition and practice impact the results, she said. What's more, the app may not be able to distinguish between different doses of THC, or if the user is under the influence of other substances as well.

Nevertheless, the app could eventually prove useful as a tool for improving users' awareness and understanding of their own impairment, which could be helpful as legal marijuana becomes more accepted and widespread in the U.S., Rees told Live Science.

"Clearly, it's a step toward helping us to mitigate some of the potential consequences of the wider uptick of marijuana use in communities where it's becoming legalized or decriminalized," Rees said.

The next steps for the app will include fine-tuning the tasks to make them even more sensitive to detecting THC impairment, and further research could help to pinpoint circumstances in which users may not be aware of how impaired they are, the researchers reported. In a second-phase study currently underway, the scientists are evaluating an optimized version of the app with tasks that take longer to complete and are more complex than in the prototype, Pabon said.

Original article on Live Science.