Cannabis UseSToP-C_PeCoGNCT04373525
Prospective Evaluation on Cognitive Function and Its Associated Genetic Vulnerability in Cannabis Users
An observational study of Cannabis Use and Neurocognitive Dysfunction, run by The University of Hong Kong at 1 site in Hong Kong.
Trial summary
Most of the studies assessing Cannabis Use Disorder (CUD) and neurocognitive functions are cross-sectional without examining the longitudinal changes in neurocognitive function at a within-subject level with respect to the continuum of cannabis use behavior, or mainly studying on the acute cannabis effect. Read more about this study
- Who is it for?
- Ages 16 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Cannabis Use, Neurocognitive Dysfunction, Genetic Predisposition
- What is being tested?
- Genome analysis
- How many people
- 110 participants
- Where
- 1 siteHong Kong
- Study dates
- 1 Nov 2020to 31 Dec 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 16 to 60 years
- All sexes
- Healthy volunteers accepted
- Child, Adult
Study population: 16-60 years old cannabis users
Who may be able to join
- Age: 16 - 60 years old at the time of enrolment
- 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
- Repeated and Active cannabis users as defined by Structured Clinical Interview for DSM-5 Disorders
Who cannot join
- Age <16 years old
- Unable to read English or Chinese
- Unable to give informed consent
- Had been diagnosed with other Substance Related Disorders, except for Tobacco Use Disorders due to the known frequent comorbid use for cannabis users (12)
- Currently taking regular prescribed psychiatric medications, including antipsychotics, antidepressants, mood stabilizers, anti-epileptics, benzodiazepines, hypnotics, and anti-cholinergic medications.
- Had been diagnosed with DSM-5 disorders, other than Cannabis Use and related disorders
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Substance Misuse To Psychiatric Disorders for Cannabis-Prospective Evaluation on Cognitive Function and Its Associated Genetic Vulnerability in Cannabis Users (SToP-C-PeCoG)
Most of the studies assessing Cannabis Use Disorder (CUD) and neurocognitive functions are cross-sectional without examining the longitudinal changes in neurocognitive function at a within-subject level with respect to the continuum of cannabis use behavior, or mainly studying on the acute cannabis effect. As for the Genome-wide Association studies, the population analyzed for addressing the underlying genetic susceptibility between neurocognitive functions and/or cannabis use or CUD were almost exclusively based on African- or European- American samples or other Caucasian subjects, and thus generalizability to Chinese or to the non-Caucasian population definitely demands more studies.
With the upsweeping statistical figures of cannabis use in Hong Kong and Asia, and the substantial falls in the perceived risk and personal disapproval from using cannabis amongst young abusers, coinciding the global advocacy of de-criminalizing cannabis and the increased availability of recreational cannabis worldwide, it is reasonable to predict that there will be a further upsurge in numbers of all aged cannabis users in Hong Kong as in the other part of the world. Therefore, the SToP-C-PeCoG study proposed here as a prospective study in assessing the longer term changes in neurocognitive functions and the associated genetic risks for those repeated and active cannabis users without psychiatric co-morbidity is definitely warranted. The PeCoG study will not only provide the scientific evidence to further unveil the harmful effects on neurocognitive functions for those self-perceived "healthy" users, but also help to raise the public awareness and to improve the understandings to the long-term detrimental effects of cannabis amongst users and non-users. Furthermore, it will provide a chance to study the associated genetic risks for cannabis abusers, in particular in the Asian minority and Chinese, on CUD and poorer neurocognitive outcomes, with genetic vulnerability being generalizable to the local population in Asia.
The current study hypothesises that cannabis abusers have neurocognitive function decline over time, and genetic vulnerability is associated with cannabis abusers who have poorer neurocognitive outcomes or with the severity of CUD.
- Being tested
- Genome analysis
- Keywords
- Cannabis, Cognition, Genetics
- Medical subject headings
- Cognition Disorders, Genetic Predisposition to Disease, Marijuana Abuse
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Genome analysisOther
Venous blood will be obtained for later genome analysis
What is being measured
The primary outcome is the main question the study is designed to answer.
Montreal Cognitive Assessment
Subject assessed with a maximum score of 30. Those who score 26 or below will consider to have mild cognitive impairment
Measured: 18 months
Frontal Assessment Battery
Subject who scores 12 or below will be considered having frontal dysexcutive function
Measured: 18 months
Wechsler Memory Scale
Subject will be assessed with the scale for their immediate, delayed, visual and auditory memory
Measured: 18 months
Genome analysis
venous blood test will be done on consented subject for genome analysis for associated single nucleotide polymorphisms on 4 related chromosomes identified from literature associated with cannabis use disorder and neurocognitive impairment
Measured: Each subject only need to have venous blood test once 1 day within their 18-months study period
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 May 2020
- Study start1 Nov 2020
- Primary completion31 Aug 2025
- Study completion31 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cannabis UseStudies of the same condition, open and under way.
- More trials run by The University of Hong KongThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 110 participants (actual)
Sponsor and investigators
- Lead sponsor
- The University of Hong Kong
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dr. Albert Kar-Kin Chung, The University of Hong Kong
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04373525
- Sponsor's protocol ID
- UW 20-189
- Acronym
- SToP-C_PeCoG
- Status last verified
- Mar 2026
- First submitted
- 23 Apr 2020
- Last updated
- 27 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: data without identifiable
Study at a glance
From the registry record, last updated by the sponsor on 27 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Substance Misuse To Psychiatric Disorders for Cannabis-Prospective Evaluation on Cognitive Function and Its Associated Genetic Vulnerability in Cannabis Users (SToP-C-PeCoG)
- ClinicalTrials.gov ID
- NCT04373525
- Acronym / sponsor ID
- SToP-C_PeCoG / UW 20-189
- Keywords
- Cannabis, Cognition, Genetics
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 110 participants (actual)
- Lead sponsor
- The University of Hong KongUniversity, hospital or other
- Study start
- 1 Nov 2020 (actual)
- Primary completion
- 31 Aug 2025 (actual)
- Study completion
- 31 Dec 2025 (actual)
- First posted
- 4 May 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Most of the studies assessing Cannabis Use Disorder (CUD) and neurocognitive functions are cross-sectional without examining the longitudinal changes in neurocognitive function at a within-subject level with respect to the continuum of cannabis use behavior, or mainly studying on the acute cannabis effect. As for the Genome-wide Association studies, the population analyzed for addressing the underlying genetic susceptibility between neurocognitive functions and/or cannabis use or CUD were almost exclusively based on African- or European- American samples or other Caucasian subjects, and thus generalizability to Chinese or to the non-Caucasian population definitely demands more studies.
With the upsweeping statistical figures of cannabis use in Hong Kong and Asia, and the substantial falls in the perceived risk and personal disapproval from using cannabis amongst young abusers, coinciding the global advocacy of de-criminalizing cannabis and the increased availability of recreational cannabis worldwide, it is reasonable to predict that there will be a further upsurge in numbers of all aged cannabis users in Hong Kong as in the other part of the world. Therefore, the SToP-C-PeCoG study proposed here as a prospective study in assessing the longer term changes in neurocognitive functions and the associated genetic risks for those repeated and active cannabis users without psychiatric co-morbidity is definitely warranted. The PeCoG study will not only provide the scientific evidence to further unveil the harmful effects on neurocognitive functions for those self-perceived "healthy" users, but also help to raise the public awareness and to improve the understandings to the long-term detrimental effects of cannabis amongst users and non-users. Furthermore, it will provide a chance to study the associated genetic risks for cannabis abusers, in particular in the Asian minority and Chinese, on CUD and poorer neurocognitive outcomes, with genetic vulnerability being generalizable to the local population in Asia.
The current study hypothesises that cannabis abusers have neurocognitive function decline over time, and genetic vulnerability is associated with cannabis abusers who have poorer neurocognitive outcomes or with the severity of CUD.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 16 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
- Study population
- 16-60 years old cannabis users
Key inclusion criteria (5 listed)
- Age: 16 - 60 years old at the time of enrolment
- 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
- Repeated and Active cannabis users as defined by Structured Clinical Interview for DSM-5 Disorders
Key exclusion criteria (6 listed)
- Age <16 years old
- Unable to read English or Chinese
- Unable to give informed consent
- Had been diagnosed with other Substance Related Disorders, except for Tobacco Use Disorders due to the known frequent comorbid use for cannabis users (12)
- Currently taking regular prescribed psychiatric medications, including antipsychotics, antidepressants, mood stabilizers, anti-epileptics, benzodiazepines, hypnotics, and anti-cholinergic medications.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Genome analysisVenous blood will be obtained for later genome analysis | Other | – |
Primary outcome
Montreal Cognitive Assessment
Time frame: 18 months
Subject assessed with a maximum score of 30. Those who score 26 or below will consider to have mild cognitive impairment
Frontal Assessment Battery
Time frame: 18 months
Subject who scores 12 or below will be considered having frontal dysexcutive function
Wechsler Memory Scale
Time frame: 18 months
Subject will be assessed with the scale for their immediate, delayed, visual and auditory memory
Genome analysis
Time frame: Each subject only need to have venous blood test once 1 day within their 18-months study period
venous blood test will be done on consented subject for genome analysis for associated single nucleotide polymorphisms on 4 related chromosomes identified from literature associated with cannabis use disorder and neurocognitive impairment
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 Mar 2026.
- Individual participant dataSharing planned: No. data without identifiable
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Cannabis Use and Neurocognitive Dysfunction, run by The University of Hong Kong at 1 site in Hong Kong.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 27 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Hong Kong. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Montreal Cognitive Assessment (time frame: 18 months). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 27 Mar 2026.