Barely Buzzed or Super Stoned An App Could One Day

November 8, 2018

How stoned are you?

This is the result of a study by researchers in a project called “Am I on drugs?” The prototype application challenges cannabis users to answer questions in which they complete a series of tasks that assess their memory, cognitive speed, reaction time and fine motor skills.

The researchers say the prototype could then give users a better understanding of the effects of THC (tetrahydrocannabinol), the compound in marijuana responsible for its psychoactive effects. That, in turn, may help them make safer choices about performing activities that may be difficult or dangerous while high, study team leader Harriet DeWitt, 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.

The high
When a person uses marijuana, THC interacts with the brain to stimulate dopamine production and create a sense of euphoria. It also binds to cannabinoid receptors in areas of the brain associated with coordination, memory, cognition and time perception, and has been found to temporarily inhibit performance in these areas – though how much of an effect it has depends on the individual and the amount and concentration of THC consumed.

To test the app, the scientists asked 24 people who don’t use cannabis on a daily basis to perform the app’s tasks on their iPhones and desktop computers after taking a pill or placebo that contained THC. Activities on the iPhone interface included a screen-click speed test, a memory game that involved clicking flower images in the correct order, and a test that required shaking the phone in response to blue dots appearing on the screen to assess reaction time.

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

The researchers found that the desktop interface could successfully detect impairments using three of the four tasks, while the iPhone app could only detect one of the tasks, Pabon said in a statement, perhaps because computer activities that take 15 to 20 minutes to complete provide more opportunities to see how THC affects users.

“The impact of THC on performance can be subtle, so we need highly sensitive tasks to detect damage,” Pabon said.

Proceed with caution.
One drawback of self-administered tests like this, however, is that if someone becomes good at performing a task through repetition and practice, the results won’t accurately reflect how impaired they are, said Vaughan Rees, a lecturer in social and behavioral sciences at Harvard’s 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 may also be affected by THC – do not appear to be assessed by the app, so the results may paint an incomplete picture of an individual’s impairment.

At this stage, Pabon said, more data needs to be collected before the app can reliably test people for THC impairment. For example, it’s important that the app take into account how a person performs on tests while awake, and how repetition and practice affect 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 also affected by other substances.

Still, the app could ultimately prove to be a useful tool for increasing users’ awareness and understanding of their impairment, which could be useful as legal marijuana becomes more accepted and widespread in the U.S., Reese told Live Science.

“Obviously, this is a step to help us mitigate some of the potential consequences of a broader rise in marijuana use in legalized or decriminalized communities,” Rees said.

The next step for the app will include fine-tuning tasks to make them more sensitive to detecting THC impairment, and further research may help identify situations where users may not be aware of their level of impairment, the researchers report. In the second phase of the study, currently underway, scientists are evaluating an optimized version of the app with tasks that take longer to complete and are more complex than the prototype, Pabon said.