This four-way, dose-response, crossover, double blind, placebo-controlled, randomised validation study investigates the responsiveness of MedDrive, a computed battery of neuropsychological tasks, to different doses of alcohol. The following hypothesis are tested: 1. Measures from MedDrive are influenced by alcohol in a dose dependent way. 2. Effects of alcohol on driving performances are correlated to measures from MedDrive in a dose dependent way. 3. Within a group of healthy young drivers, MedDrive shows consistent results over repeated measures (ICC≥0.7). 4. MedDrive models effects of alcohol on driving performances better than does the UFOV or the trial making task.
Background: There is an increasing need for physicians to advice patients on their fitness to drive. Current guidelines underline the limitations of existing instruments and the poor adaptability of batteries of neuropsychological tests assessing fitness to drive in both experimental and primary care settings. The investigators therefore developed MedDrive, a free, reliable, computer based measuring instrument capable of detecting effects of age and drugs on cognitive functions considered as essential for driving. Objectives: This study aims to test MedDrive responsiveness to different blood alcohol concentrations (BAC) and validate these measures against performances on a driving simulator. It also aims to measure MedDrive's reliability following repeated measures during the training phase, to compare MedDrive's performances in measuring effects of different BAC against the UFOV, and to model MedDrives measures to predict behaviour on the simulator. Finally, this study also includes a nested experimental study measuring effects of alcohol on attention. Methods: Using Widmark's formula, 16 healthy young drivers are given cranberry juice with different doses of ethanol to bring their BAC to 0 g/L, 0.5 g/L, 0.65 g/L, and 0.8 g/L. They are blinded to the presence of ethanol by inhaling vapors of ethanol just before drinking. BAC is maintained during the entire experiment by using a breathalyser and administrating drinks throughout the experiment. Three scenarios are planned on a driving simulator (StSoftware PvW-2010), a road tracking task, a car following task, and a car following task including dual tasking using peripheral vision.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
During a 45 min period, investigators will ask participants to drink 500ml of cranberry juice, 100 ml at a time each 5 minutes. Depending of the allocation, these drinks will contain more or less alcohol. Pure ethanol will be used mixed with the beverage. The amount of alcohol to dilute in the drink will be calculated using Widmarks formula. Participants will move to the simulator room 20 minutes after having finished drinking the first 500 ml. To maintain the BAC level, investigators will use a breathalyser and provide 100 ml cranberry juice every 20 minutes with the amount of necessary alcohol. The person administrating drinks will hand over the drinks and make sure the participants breaths in before taking a sip, thereby inhaling alcohol vapour from the lid and keeping them blinded to the content.
100 mL cranberry juice is provided in a 250 ml container.
Institute of Legal Medicine, University of Geneva
Geneva, Canton of Geneva, Switzerland
central visual processing time
Corresponds to the duration of exposure in ms for a 37.5% threshold for correct guesses adjusted for chance for central vision in the Visual Recognition Task (Task 1) in MedDrive.
Time frame: 1 hour post-intervention
peripheral visual processing time
Corresponds to the duration of exposure in ms for a 43.8% threshold for correct guesses adjusted for chance for peripheral vision in the Visual Recognition Task (Task 1) in MedDrive.
Time frame: 1 hour post-intervention
dual task processing time
Corresponds to the duration of exposure in ms for a 48.7% threshold for correct guesses adjusted for chance for simultaneous central and peripheral vision (dual tasking) in the Visual Recognition Task (Task 1) in MedDrive.
Time frame: 1 hour post-intervention
neutral response time
Corresponds to the average response time in ms adjusted for learning effect for participants to respond to a peripheral stimuli during the Central Cue Attention Task (Task 2) in MedDrive.
Time frame: 1 hour post-intervention
conditioned alerting gain
Corresponds to the average gain in response time (ms) over the neutral condition after participants are warned of the imminent exposure to a peripheral stimuli during the Central Cue Attention Task (Task 2) in MedDrive.
Time frame: 1 hour post-intervention
orientation gain
Corresponds to the average gain in response time (ms) over the neutral condition after participants are shown where the peripheral stimuli is to show up during the Central Cue Attention Task (Task 2) in MedDrive.
Time frame: 1 hour post-intervention
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DIAGNOSTIC
Masking
DOUBLE
Enrollment
21
attention shift response time
Corresponds to the average response time in ms to detect the orientation of a given moving target during the Movement Detection Task (Task 3) in MedDrive.
Time frame: 1 hour post-intervention
distance to first cue
Corresponds to the geometrical mean of distances in mm between the true location of the first cue and its indicated location during the Memory Decay of Spatial Resolution Task (Task 4) in MedDrive.
Time frame: 1 hour post-intervention
distance to last cue
Corresponds to the geometrical mean of distances in mm between the true location of the last cue and its indicated location during the Memory Decay of Spatial Resolution Task (Task 4) in MedDrive.
Time frame: 1 hour post-intervention
spatial resolution decay
Corresponds to the loss in precision for each extra cue shown during the Memory Decay of Spatial Resolution Task (Task 4) in MedDrive (ln(mm)/cue).
Time frame: 1 hour post-intervention
Useful Field of View
The UFOV is a neuropsychological task which provides four outputs: visual processing, divided attention, selective attention, and overall risk
Time frame: 1 hour post-intervention
Trial Making Task
The duration of tasks TMT-A and TMT-B are provided in seconds
Time frame: 1 hour post-intervention
StSoftware driving simulator
Standard lateral deviation from the center of the road during the road tracking task, and gain and delay during the car following tasks
Time frame: 1 hour post-intervention