This study examines the effect of regular naltrexone dosing on disordered gamblers. Gamblers will also be scanned pre- and post-treatment where we will investigate the functional changes to tasks designed to engage brain region associated with gambling and addiction. These changes will be correlated with treatment outcomes and urge scores.

This study will investigate the effects of regular dosing of naltrexone for the treatment of disordered gambling. It will also examine the changes of neurological functioning to tasks associated with addiction. Converging evidence suggests that disordered gambling shares similarities with substance dependence and disordered alcohol use. Naltrexone is a medication that is used to reduce the cravings and euphoria from opioids and alcohol use and some studies have shown that it also has efficacy as a treatment for problematic gambling. Pilot data suggest the prefrontal cortex is activated for a healthy subject during a delay-discounting task, possibly indicating some consideration of the delayed value of a hypothetical money amount. If discounting rates can be correlated with treatment outcomes and neurological activation, these tasks may provide a new predictive tool for treatment outcome. However, no previous study has examined the neurological changes from pharmacological treatments of gambling. This study will provide data on the differences between pre- and post-treatment of regular naltrexone dosing for disordered gamblers

Inclusion Criteria:

• 18-70 years of age.
• Provide written consent.
• Evidence of Disordered Gambling (DSM-V; American Psychiatric Association, 2013)
• Seeking treatment for disordered gambling, referrals, or responding to information about the study presented in the media.
• Primarily Video Lottery Terminal gamblers (to standardize gamblers and as we are using stimuli in the gambling stimuli task that is similar to video lottery terminals displays so gamblers will be familiar with these images).
• Attendance at Alberta Health Service Evening Gambling Intensive Program (EGRIP) or similar
• English speaking

Exclusion Criteria:

• Evidence of a current significant medical illness, or unmanaged psychiatric or neurological disorder.
• Positive urine specimen to drugs of abuse.
• History of a traumatic brain injury or loss of consciousness (10 minutes or more).
• History of evidence of claustrophobia
• Left handed.
• Any condition or circumstance that prohibit imaging sessions such as metal implants.
• Contraindications to clinical doses of naltrexone.
• History or evidence of allergic reactions to naltrexone administration (i.e., rash, itching/swelling, severe dizziness, or trouble breathing).
• Concurrent use of additional alcohol dependence medication e.g. disulfiram.
• Evidence of current illicit opioid use
• Use of medications containing opioids/opiates
• Uncorrected visual impairment
• Evidence of brain abnormalities from structural scans
• Evidence of heart, liver or kidney failure.
• Failure to attend weekly EGRIP counselling sessions or similar
• Pregnant

Other Requirements:

• If sexually active must use contraception
• Cannot make ovum or sperm donation during study and six-months thereafter