In Hong Kong, although the total number of drug abusers is trending down in recent years, the number of cannabis users continues to surge. The misuse of cannabis, if left unattended, predisposes various degrees of dependence and use disorders, which could later on induce psychotic disorders and schizophrenia. Effective strategies combating cannabis dependence and cannabis use disorder (CUD) are therefore warranted.

Exercise presents as a low-cost and low-stigma alternative to traditional pharmacotherapy and psychotherapy in the treatment of substance use disorders, which also promotes physical well-being with virtually no side effects. While exercise has some success in treating use disorders of stimulants, alcohol, and tobacco, evidence of its effects on CUD remains scarce. Hence, the present study will be conducted to assess the effectiveness of a 12-week aerobic exercise training regimen on reducing cannabis dependence and the severity of CUD.

Participants with cannabis dependence will be randomly assigned to either the exercise or the control group. Participants assigned to the exercise group will partake in a 12-week aerobic exercise training program of vigorous-intensity using indoor bikes, whereas those assigned to the control group will perform sham exercise of very light-intensity on indoor bikes. The 12-week study is divided into three (3) 4-week phases:

1. Intensive Intervention - all participants will exercise twice a week under supervision.
2. Active Intervention - all participants will exercise once a week under supervision.
3. Passive Maintenance - no supervised exercise sessions will be provided. All participants will receive exercise reminders via weekly text messages.

Cannabis use-related, cognitive, and physical outcomes will be assessed every 4 weeks, whereas withdrawal symptoms will be assessed and urine quick test administered every week.

Inclusion Criteria:

• Young adults of 18-40 years old

• Able to read and communicate in English and/or Chinese

• Able to give informed consent

• Using cannabis or marijuana as the primary psychoactive substance of abuse

• Suffering from cannabis addiction, defined by:

  i. Cannabis Dependence with an SDS score ≥ 3, or ii. Cannabis Use Disorder according to the Diagnostic and Statistical Manual of Mental Disorders 5th Edition (DSM-5), or iii. Cannabis Harmful Use or Dependence according to the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) or Clinical descriptions and diagnostic requirements for International Classification of Diseases 11th Revision (ICD-11) mental, behavioral, and neurodevelopmental disorders.

Exclusion Criteria:

• Age < 18 or > 40 years old

• Unable to read English or Chinese

• Unable to give informed consent

• Absolute and/or relative contraindications to exercise training as indicated by the Physical Activity Readiness Questionnaire for Everyone (PAR-Q+) and the electronic Physical Activity Readiness Medical Examination (ePARmed-X+)

• Had been diagnosed with the following disorders, including:

  i. Neurodevelopmental Disorders DSM-5: Intellectual Disabilities, Communication Disorders, Specific Learning Disorder, Autism Spectrum Disorder and Motor Disorders ICD-11: Disorders of intellectual development (6A00), Developmental speech or language disorders (6A01), Autism spectrum disorder (6A02), Developmental learning disorder (6A03), Developmental motor coordination disorder (6A04), Stereotyped movement disorder (6A06), Primary tics or tic disorders (8A05.0) ii. Other DSM-5 defined Substance Use Disorder greater than mild in severity (i.e., severity score ≥ 2), except for tobacco or caffeine iii. Neurocognitive Disorders (DSM-5, or ICD-11 6D70-72 & 6D80-86)