Introduction to the DRUID app, Inc
How to Measure Impairment from Cannabis
As the worldwide legalization of cannabis accelerates, impairment from cannabis has been raised as a concern for cannabis users’ driving and workplace performance, with potentially serious implications for public safety. Generally, states consider driving under any level of impairment illegal. Becoming impaired from cannabis and then driving is definitely something you shouldn’t do.
How is cannabis impairment determined? Often touted as the “Gold Standard,” limits on blood THC levels have been written into the laws of several states that have legalized cannabis, e.g., a 5 ng/mL blood limit in Washington state. The problem with this approach is that there is no scientific basis for such THC limits, according to the NHTSA 2017 report to Congress. Because THC is lipophilic, it can remain in the body’s fat cells for weeks or even months, long after impairment is gone. The availability of the new DRUID® impairment evaluation app (in the App Store and Google Play) has enabled the measurement of cognitive/motor skills outside the laboratory. The DRUID® app measures reaction time, and hand eye coordination and the capacity to do “divided attention tasks”; and unlike all other cannabis impairment apps, DRUID® has been scientifically validated.
The DRUID® app represents a paradigm shift in the way impairment should be measured. Because the BAC=.08 level has been convenient for prosecutors to get impaired-driving convictions, there has been a pursuit world-wide for a “cannabis breathalyzer.” However, because individuals who consume cannabis frequently can develop tolerance, there is no “per se” level of THC in the body that reliably demonstrates impairment, like there is for alcohol. DRUID® does not tell you if it is safe for you to drive—it reports if it finds any evidence of impairment. It’s important to recognize that individuals can respond very differently to the same amount of cannabis. How much impairment a person experiences from consuming cannabis will depend on multiple factors, including: the THC potency of the cannabis consumed; the amount of cannabis consumed; the frequency of cannabis use for past year; and the recent frequency of cannabis use (e.g., previous day).
The DRUID® App
With substantial NIH grant support, multiple researchers have validated the accuracy with which DRUID® measures impairment. DRUID®’s ability to measure impairment from alcohol was validated in a peer-reviewed publication, and preliminary data from two cannabis-administration studies using DRUID® indicate the accuracy of the app to distinguish different levels of impairment from different amounts of THC consumed, e.g., 0mg, 5mg and 20mg.
DRUID® presents four tasks that measure reaction time, decision making, hand-eye coordination, time estimation and balance, with three of the tasks being divided attention tasks. Hundreds of data points are integrated statistically and transformed to an overall impairment score ranging from 0 to 100; most scores are between 30-70. A typical sober score for DRUID® is generally in the range of 32-42.
Task 1 measures reaction time and decision making—shapes flash on the screen for ½ second, either a square or a circle. The user touches the screen where one shape appeared or touches the oval shape at the top of the screen when the other shape appears. DRUID® measures reaction time and errors in choosing the correct action. Task 2 measures reaction time and time estimation—a person counts for 15 seconds and then presses a “Stop” button while touching the screen where circles flashed. Task 3 measures hand-eye coordination with a circle that moves around the screen. The user keeps their finger on the circle as much as they can and counts the number of squares that flash on the screen. Task 4 uses the device’s accelerometer to test stability and balance, a key element of the Standard Field Sobriety Test that has been found to relate to cannabis intoxication. Users stand on each leg for 15 seconds, holding the device as still as possible.
The pattern of shapes that DRUID® presents in Tasks 1-3 is different every time a person uses DRUID®. This means a user cannot memorize or anticipate where the circles/squares will flash on the screen. Not following the instructions for using DRUID®, e.g., holding the device in two hands rather than one, can produce inaccurate results.
Figure 1 shows cannabis impairment measured by DRUID® from the same individual after vaping 0.4 gram of cannabis on two consecutive days. As is apparent, DRUID® produces very reliable impairment scores over the span of 90 minutes. The DRUID® curves in Figure 1 show a level of impairment that parallels users’ subjective experience from cannabis, reaching peak intoxication in about 30 minutes, and gradually decreasing over time as the body metabolizes the drug over the subsequent hours. Given that hundreds of individual measures (reaction times, errors, etc.) are combined into a single impairment score, the fact that these two curves are so close is evidence of DRUID®’s reliability.
The DRUID® app has the potential to be the gold standard for the measurement of impairment. It is inexpensive, portable, easy to use, quick and non-invasive. Because DRUID® has been scientifically calibrated against the .08 blood alcohol level that people generally understand, and because DRUID® can assess the level of impairment from different amounts of THC consumed, it provides a unique tool for anyone to assess their own level of impairment, regardless of the source.
While providing an accurate way to assess impairment in driving stops by law enforcement could be a major application of the DRUID® app, I invented DRUID® to stop impaired people from getting in the car in the first place. And, there are also significant medical cannabis applications for the DRUID® app. Doctors and patients can use the app to help determine the best strain and dose that treats a person’s symptoms with the least impairment. My next article will discuss multiple applications of DRUID® for cannabis consumers.