A1150
Title: A case study of pupil dynamics after cannabis consumption using crossed multilevel function-on-scalar regression
Authors: Julia Wrobel - Emory University (United States) [presenting]
Abstract: Marijuana is now legal for recreational or medical use in 41 states. Due to long-standing federal restrictions on cannabis research, the implications of cannabis legalization on traffic and occupational safety are understudied. Accordingly, there is a need for objective and validated measures of cannabis impairment that may be applied in public safety and occupational settings, such as post-crash or accident investigations. Identifying a reliable biomarker of recent cannabis use has proven challenging, but pupil response to light may offer an avenue for detection that outperforms typical sobriety tests. A wearable pupillometer is used to collect 5-second trajectories of change in pupil size after a light stimulus to investigate pupil light response as a biomarker of recent cannabis use. These "pupil trajectories" are collected for both the left and right eye before and at 45 and 80 minutes post-cannabis consumption for 120 subjects, resulting in 720 functional observations of pupil response to light. A new functional regression model is then developed to infer pupil dynamics in response to light for those who used and did not use cannabis and at different times post-cannabis use. The model modifies methodology on structured functional principal components analysis to provide appropriate inference for the complex repeated-measures structure of the functional observations. The method's performance is evaluated in simulations, and results for the motivating data are presented.
