The Efficacy and Neurobehavioural Mechanism of Cannabidiol (CBD) for Alcohol Dependence

To assess whether acute ingestion of CBD can modulate subjective measures of alcohol cue elicited craving. This will be measured during the fMRI scan using the Visual Analogue Scale. This scale will assess alcohol craving, thirst and anxiety.

To assess whether acute ingestion of CBD can modulate subjective measures of alcohol cue elicited craving. This will be measured before and after the fMRI scan using the Alcohol Urge Questionnaire (AUQ). This Questionnaire consists of 8 questions that are scored on a Likert scale of 7 points. Two of the questions are reversed scored. Total score is computed by averaging the item scores. A greater score indicates greater craving.

To assess whether acute ingestion of CBD can modulate subjective measures of positive and negative mood states following alcohol cues. This will be measured before and after the fMRI scan using the Positive and Negative Affect Schedule (PANAS).

Measured by cumulative scores on the DASS-21 Anxiety Scale. This scale has a minimum score of 0 and maximum score of 21. A higher score indicates more anxiety.

Measured by cumulative scores on the DASS-21 Depression Scale. This scale has a minimum score of 0 and maximum score of 21. A higher score indicates greater depression.

Measured by cumulative scores on the DASS-21 Stress Scale. This scale has a minimum score of 0 and maximum score of 21. A higher score indicates more stress.

As measured by the ISI (Insomnia Severity Index). This Index has a minimum score of 0 and a maximum score of 28. The higher the score indicates more severe insomnia.

To assess whether acute ingestion of CBD has any impact of sleep. This will be measured by an Actiwatch. The Actiwatch records motion and light to determine information about participants sleep and wake patterns. The participants will wear this watch for 48 hours on two separate occasions.

To assess whether CBD treatment can reduce participants need to use alcohol to attenuate tension states (such as anxiety) as measured by the Tension Reduction subscale of the Alcohol Expectancy Questionnaire. Higher scores indicate greater reliance on alcohol to reduce tension/ anxiety.

To examine the adverse consequences a participant has experienced in their lifetime due to alcohol abuse in five areas: Interpersonal, Physical, Social, Impulsive, and Intrapersonal. This is measured using the Drinker Inventory of Consequences Lifetime Edition (DrInC-2L). Higher scores indicate more consequences.

To examine the adverse consequences a participant has experienced in the last 3 months due to alcohol abuse in five areas: Interpersonal, Physical, Social, Impulsive, and Intrapersonal. This is measured using the Drinker Inventory of Consequences Recent Edition (DrInC-2R). Higher scores indicate more consequences.

The BIS/BAS Scale is a 20-item self-report questionnaire designed to measure two motivational systems: the behavioral inhibition system (BIS), which corresponds to motivation to avoid aversive outcomes, and the behavioral activation system (BAS), which corresponds to motivation to approach goal-oriented outcomes.

To assess an individuals obsessive thoughts about alcohol use and compulsive behaviours towards drinking as measured by the Obsessive Compulsive Drinking Scale. Six of the questions measure to obsession and eight of the questions measure compulsivity. Higher scores on these subscales indicate more obsession and compulsion, respectively.

To measure an individual's self-confidence in avoiding alcohol through the Alcohol Abstinence Self-Efficacy Scale (AASE). There are 20 questions and each is scored from 0 to 4. Higher scores on this scale indicate more self-confidence.

To assess an individual's reactions to situations that are ambiguous, the consequences of being uncertain, and attempts the individual might make to control the future. This will be measured through the Intolerance of Uncertainty Scale (IUS). This scale includes 27-items that are scored on a Likert scale (1 - Not at all characteristic of me to 5 - entirely characteristic of me). All scores are summed up and a higher score indicates greater inability to deal with uncertainty.

To assess an individual's impulsivity across four domains: urgency, lack of premeditation and perseverance, and sensation seeking. This will be measured through the Impulsivity Scale (UPPS). Greater scores on this scale indicate greater impulsivity.

To assess an individual's severity of alcohol withdrawal through the Clinical Institute Withdrawal Assessment of Alcohol Scale - Revised (CIWA-Ar). Greater scores on this scale indicate the participant is experiencing greater alcohol withdrawal symptoms.

To assess an individual's automatic action tendencies (either approve or avoid) towards alcohol. This will be measured through the Approach Avoidance Task (AAT).

To assess an individual's response time and visuospatial skills through the Trail Making Test Part A (TMT-A).

To assess an individual's set-shifting flexibility, attention and inhibition through the Trail Making Test Part B (TMT-B).

To assess an individual's risk taking behaviour measured through the Balloon Analogue Risk Task (BART).

To assess an individual's decision making skills measured through the Columbia Card Task (CCT).

To assess an individual's ability to inhibit prepotent responses measured through the Stroop task.

To assess an individual's capacity to update working memory information measured through the N-back task.

To assess an individual's capacity to shift between two tasks measured by the Number Letter task.

As measured by differences in blood sampling levels of glutathione.

As measured by differences in blood sampling levels of cortisol. This will be measured at rest, before the fMRI scan and following the fMRI scan.