The effects of two doses of alcohol on eye movement behaviour during driving

Over the three-week experimental period, participants will receive all of the experimental doses. One dose (weighted and sex-dependent treatment) will be taken orally (by mouth) under supervised administration at each session [i.e. active treatment(s): weighted dose of alcohol (vodka) with orange juice to reach 0.05% Blood Alcohol Concentration (BAC); weighted dose of alcohol (vodka) with orange juice to reach 0.08% Blood Alcohol Concentration (BAC); or placebo treatment, weighted dose of alcohol-free vodka with orange juice] and the order of dosing will be randomised. The active treatments are: 1. Weighted and sex-specific dose of vodka and orange juice drink to achieve 0.05%BAC 2. Weighted and sex-specific dose of vodka orange juice drink to achieve 0.08%BAC This will be achieved using an adjustable calculation based on the Watson method of dosing per estimated total body water for men and women (derived from height and weight) rather than only body weight, as per the equation below: 1. Total Body Weight (TBW) men (Litres, L) = 2.2447 - (0.09516 x age) + (0.1074 x height) + (0.03362 x weight) 2. TBW women (L) = 2.097 - (0.1069 x height) + (0.2466 x weight) For an average 70 kg male person to achieve 0.05%BAC, this will require dosing of ~111g of 40% alcohol, or 4 standard drinks (30mL shots) with 334g mixer orange juice (total drink 445g). For 0.08%BAC, it will require ~175g of 40% alcohol, or ~5.7 standard drinks (30mL shots) with 527g mixer orange juice (total drink volume 703g). A one-week washout period will occur between testing sessions. Prior to dosing at each testing visit (each at V1, V2 and V3), participants will provide one saliva sample to screen for evidence of recent use of drugs [amphetamine/d-methamphetamine, 3,4- methylenedioxymethamphetamine (MDMA), cocaine, cannabis (del ta-9-tetrahydrocannabinol) and opiates] using the Securetec DrugWipe 6s device. This screening assessment requires an absorbent pad to be placed over the tongue for approximately 20 seconds. 1ml of saliva will be taken per sample, therefore approximately 3ml in total over each of the three experimental sessions. A sample volume of less than 10 micro litres is sufficient for analysis. The device is wiped on the tongue, when the colour has changed from pink to yellow there is the required amount of saliva to obtain the results. A registered research nurse trained in venepuncture or a qualified venepuncture technician will collect two blood samples at each testing session (each at V1-V3), at ~1 and ~2.5 hours post treatment administration. The Cambridge Neuropsychological Test Automated Battery (CANTAB) will be used to assess the cognitive effects of the intervention. Four tasks will be used in this study to assess such as fluid reasoning, executive function, attention, visual processing, short-term and long-term memory, processing speed and reaction/decision speed specifically: Multitasking Test, Spatial Working Memory, Rapid Visual Information Processing, Reaction Time and Spatial Span. Participants will be assessed at approximately 85 minutes post-dosing. Driving performance with simultaneous eye movement monitoring will be assessed using the Forum 8 driving simulator, and driving performance will be assessed three times per study session, for a 20 minute duration each. The simulator consists of a car unit with adjustable car seats and a dashboard and includes a steering wheel, turn sign indicators, gear lever, brake and accelerator pedals for vehicle control. The system generates realistic roadway scenery which is presented on three integrated TV screens 1.90 meters in front of the centre of the steering wheel. The speed and gear number are displayed on the dashboard and screen. Auditory feedback is provided by speakers and included the sound of the engine, braking, speeding in curves, and driving off-road. The simulation scenarios will incorporate features of a highway and suburban environment. Driving assessment will take place at baseline, at approximately 45 minutes and again at approximately 150 minutes post dosing. The overall anticipated duration of each visit is 3.5 hours