Sensitivity, Specificity and Accuracy of a Novel EEG-Based Objective Test, the Cognalyzer®, in Detecting Cannabis Psychoactive Effects

Abstract

Introduction Current standards for identifying recent cannabis use are based on body fluid testing. The Cognalyzer ® is a novel electroencephalography (EEG) measurement device and algorithm designed to objectively characterize brainwave alterations associated with cannabis. The objective of this study was to assess the accuracy, sensitivity and specificity levels of the Cognalyzer ® to characterize brainwave alterations following cannabis inhalation. Methods Seventy-five participants, aged 19–55 years, were enrolled, and oral fluid samples were collected pre-cannabis inhalation. EEG and subjective drug effects questionnaire (DEQ) were administered pre- and post-ad libitum cannabis inhalation. Fifty participants remained in the clinic for 4 h post-inhalation. Blinded analyses of the EEG files were conducted by Zentrela Inc. using two versions (V1 and V2) of the Cognalyzer ® algorithm. Pre- vs. post-inhalation comparison status was characterized by the Cognalyzer ® and summarized for: sensitivity, specificity, accuracy, percent false positive, percent false negative and positive and negative predictive value. The null hypothesis was tested using McNemar’s test. Cognalyzer ® results pre- and post-inhalation were combined with the oral fluid tetrahydrocannabinol (THC) concentration to evaluate potential to improve current drug testing. Results The two versions of the Cognalyzer ® algorithm had similar diagnostic results. Diagnostic outcomes were improved when participants with missing EEG recordings or electrode placement errors were removed. The Cognalyzer ® accuracy was 85.5% and 83.9%, sensitivity was 87.1% and 88.7%, and specificity was 83.9% and 79.0% for algorithm V1 and V2, respectively. Combining Cognalyzer ® results with oral fluid concentrations reduced false-positive oral fluid test results by up to 49%. Conclusion The Cognalyzer ® characterized brainwave alterations associated with cannabis inhalation with high levels of accuracy in a population of participants with varied cannabis inhalation histories, relative to the comparison standard of pre- vs. post-inhalation status. The Cognalyzer ® allows the results to be generalized to the larger population addressing a limitation in currently accepted standards.

Use of a Novel EEG-Based Objective Test, the Cognalyzer®, in Quantifying the Strength and Determining the Action Time of Cannabis Psychoactive Effects and Factors that May Influence Them Within an Observational Study Framework

“…The Cognalyzer ® algorithm, employed in the manner described here, is able to both detect and quantify the PE of cannabis on brain activity measured using EEG after inhalation. When a threshold is applied to the calculated PE level for a participant, the algorithm is up to 85.5% accurate at blindly classifying whether a participant is currently experiencing an altered brain state [ 28 ]. This capability is comparable to the accuracy of current drug testing methods such as saliva or blood tests; however, these methods only detect the presence of the psychoactive substance indicating recent use and cannot directly quantify the magnitude of the PE.…”

“…The results from two candidate algorithms using slightly different parameter weightings were evaluated, Cognalyzer ® version 1 (V1) and version 2 (V2). All EEG data files were blinded by KGK Science Inc. prior to sending to Zentrela Inc. for analysis [ 28 ].…”

“…It is a portable and objective solution that can be applied to workplace or roadside testing. The accuracy, sensitivity and specificity of two versions of the Cognalyzer ® algorithms in distinguishing between EEG activity from pre- and post-inhalation of cannabis have been previously published [ 25 ]. The accuracy was 85.5% and 83.9%, sensitivity was 87.1% and 88.7% and specificity was 83.9% and 79.0% for the two algorithm versions, V1 and V2, respectively.…”

“…The accuracy was 85.5% and 83.9%, sensitivity was 87.1% and 88.7% and specificity was 83.9% and 79.0% for the two algorithm versions, V1 and V2, respectively. For more information on the psychometric properties of our and other tests when used to determine potential cannabis impairment, please refer to our previous publication [ 25 ]. The objective of this study was to measure the time action curve of cannabis’ psychoactive effects on a 0–100 scale for up to 4 h post-inhalation of cannabis.…”

Cannabis and Driving

“…Several such candidate measures are currently undergoing testing. These include Milburn's DRUID test battery (128)(129)(130), assessments of postural instability using electronic devices, measurements of brain state using portable EEG devices (131), pupillary responses to flashes of light, laptop-based cognitive test batteries, and hand-held, instrument-based cognitive testing devices, such as the Intoximeter 2 . It should be emphasized that all of these investigations are preliminary, and no valid, reliable screening paradigm is yet available.…”