Rationale
Illicit drug use can increase driver crash risk due to loss of control over vehicle trajectory. This study asks, does recreational use of ±3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) and tetrahydrocannabinol (THC; marijuana) impair cognitive processes that help direct our safe movement through the world?Objective
This study assesses the residual effects of combined MDMA/THC use, and of THC use alone, upon perceived trajectory of travel.Methods
Perception of self-motion, or heading, from optical flow patterns was assessed using stimuli comprising random dot ground planes presented at three different densities and eight heading angles (1, 2, 4 and 8° to the left or right). On each trial, subjects reported if direction of travel was to the left or the right.Results
Results showed impairments in both drug groups, with the MDMA/THC group performing the worst.Conclusions
The finding that these psychoactive agents adversely affect heading perception, even in recently abstinent users, raises potential concerns about MDMA use and driving ability.Keywords MDMA - Driving - THC - Substance abuse - Visual motion