This study is designed to improve our understanding of brain function in gambling disorder. The main purpose of the study is to measure how the brain’s so-called reward system reacts while engaged in gambling-related activities and while exposed to gambling-related stimuli in men addicted to gambling and age-matched non-gambling healthy individuals (‘controls’).

Both for the comprehension of gambling disorder specifically and addictions in general, it is important to better understand the mechanisms underlying the suspected “hi-jacking” of the brain’s reward system by addiction behaviour.

Such understandings can improve our ability to develop better treatments for individuals with addictions. We will use sensitive brain-imaging techniques (functional magnetic resonance imaging, or fMRI) to detect subtle changes in function within the brains reward system while performing a gambling task as well as while watching gambling and non-gambling-related video clips. An additional intention with this study, is that the results will help us develop new and even more sophisticated brain imaging methods that will allow to measure brain activity (as we do in this study) and brain messenger molecules at the same time. Such methods would be highly useful for brain science in a broad sense, even beyond addiction research.

You will have 2x study visits. The first will be a screening and EEG testing at St Charles Hospital, London and visit 2 will be at Invicro, Hammersmith Hospital. These two visits could be on the same day (each lasting 3.5 hours) or could be up to two weeks apart.

All participants:

A participant will be eligible for inclusion in this study only if all of the following criteria apply:

1. Male participants aged between 20 and 65 years old.
2. The participant is capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form.
3. The participant is able to read, comprehend and record information spoken or written in English.
4. A signed and dated written informed consent is obtained from the participant.
5.  Additional inclusion criteria for healthy volunteers.

Healthy as determined by a responsible physician, based on a medical evaluation including medical history, physical examination and psychiatric evaluation. A participant with a clinical abnormality may be included only if the investigators concur that the finding is unlikely to jeopardize either participant safety or study integrity.
 Additional inclusion criteria for gambler disorder participants:

1. Gambling disorder according to DSM-5 diagnostic criteria.
2. GDs can be enrolled into the study from their initial clinical evaluation appointment at the clinic, through to the beginning of their treatment at the clinic

All participants:

1. A participant will not be eligible for inclusion in this study if any of the following criteria apply:
2. Any current psychiatric diagnosis according to DSM-5, except Gambling Disorder (for GDs) or Tobacco Use Disorder (for all). Screening for psychiatric diagnoses will be performed by a clinical psychiatrist screening and will cover exclusion of the following conditions: major depressive disorder, bipolar disorder, generalized anxiety disorder, panic disorder, agoraphobia, social anxiety disorder, obsessive-compulsive disorder, post-traumatic stress disorder, psychotic disorder, and eating disorder.
3. Current or past dependence on other substances of abuse, except nicotine, will not be permitted but previous recreational use will be permissible. No use of any illegal drugs or drinking alcohol >21 units/week during the last two weeks prior to assessment.
4. At assessments, the participant has a positive pre-study drug/alcohol result on testing. A minimum list of drugs that will be screened for includes amphetamines, cocaine, opiates, cannabinoids and benzodiazepines.
5. The participant is taking any psychotropic medication or medication that interacts with the fMRI tasks. Other medications will be allowed if in the opinion of the investigators determine the medication will not interfere with the study procedures or compromise participant safety.
   Medical condition that is unsuitable for the EEG components of the study (e.g., epilepsy, severe migraine).
6. History of or suffers from claustrophobia or feels that he will be unable to lie still on his back in the
7. MRI scanner for a period of up to 1.5 hours.
8. Presence of a cardiac pacemaker or other electronic device or ferromagnetic metal foreign bodies as assessed by a standard pre-MRI questionnaire.
9. History or presence of a neurological diagnosis, not limited to but including for example, stroke, epilepsy, space occupying lesions, multiple sclerosis, Parkinson's disease, vascular dementia, transient ischemic attack, that may influence the outcome or analysis of the scan results.
10. Unwillingness or inability to follow the procedures outlined in the protocol.
11. Clinically significant head injury (e.g., requiring medical or surgical intervention).

Additional exclusion criteria for healthy volunteers:

1. Any previous psychiatric diagnosis according to DSM-5, except Tobacco Use Disorder.

If you have a Gambling addiction and would like to take part in the study, we are currently recruiting from the National Problem Gambling Clinic. You are able to self-refer to this service and specify that you would also like to take part in this study.

Work from this study has recently featured in the BBC documentary, Paul Merson: Football, Gambling and Me https://www.bbc.co.uk/programmes/p09y3lgl