Mapping short-term brain changes in cannabis users: an fMRI study
Moderate-to-severe Cannabis Use Disorder (CUD), as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)
Blinding details: The study includes “blinded” and “unblinded” testers, with distinct roles described below. 1. Selected researchers will administer face-to-face clinical and cognitive assessment, and MRI to the participant, without knowing which intervention condition cannabis users have been allocated to. These researchers will be referred to as “blinded” testers. 2. Selected researchers will be unblinded to each CUD participant’s allocation to the three intervention conditions. These will be referred to as “unblinded” testers. Unblinded testers will not administer any testing other than the intervention. Specifically, “unblinded” testers will: 1.1. Allocate CUD participants to one of the three distinct intervention conditions in a pseudo-randomised fashion. This is to ensure group matching for age and sex across all three intervention conditions and the non-using control group, and for the number of CUD symptoms at baseline across the three intervention conditions. 1.2. Administer the intervention at baseline and follow up face-to-face assessments. 1.3. Administer scales immediately before and after the intervention at baseline and follow up face-to-face assessments, to monitor its effectiveness. 1.4. Give participants information and material relevant to the online practice of the intervention. 1.5. Monitor the participant’s completion of the online daily intervention for the 2-week intervention period (e.g. VAS scales and/or audio tracks). 1.6. Communicate with the participants about any issues during the intervention period. 1.7. Debrief the participants on the intervention. OVERALL STRUCTURE OF THE ASSESSMENT AND INTERVENTION PROTOCOL 1. THREE MAIN PHASES The testing protocol comprises three main phases: 1.1. Face-to-face baseline assessment, ~4 hours (here on referred to as ‘baseline assessment’) 1.2. ~2-week daily off-site, online intervention, ~10-15 minutes daily 1.3. Face-to-face follow up assessment, ~3 hours (~2-weeks post baseline) (here on referr
Inclusion criteria for all participants: 1. Aged 18 to 55 years 2. Normal-to-corrected vision 3. Fluent in English 4. Meeting safety criteria for MRI scan Inclusion criteria for cannabis users: 1. Daily/almost daily (>3 days per week) cannabis use for >12 months 2. CUD 4+ DSM-5 symptoms 3. Tried to quit/reduce cannabis use at least once within the past 24 months
Exclusion criteria for all participants: 1. Any illicit substance and alcohol use for 12 hours before assessment (confirmed by self- report) 2. Currently using prescription medication that affect the central nervous system 3. Current or past diagnosed psychiatric disorders 4. Any current severe psychiatric diagnosis, excepting diagnoses of depression or anxiety 5. History of any neurological disorders 6. History of acquired or traumatic brain injury 7. Currently pregnant 8. Suicidality Exclusion criteria for cannabis users: 1. Significant use or dependence on alcohol and any illicit substances other than cannabis 2. Illicit drug use past 4 weeks (other than cannabis) Exclusion criteria for non-cannabis using controls: 1. Significant use or dependence on alcohol and any illicit substances 2. Illicit drug use past 4 weeks