Prospective Evaluation on Cognitive Function and Its Associated Genetic Vulnerability in Cannabis Users (SToP-C_PeCoG)

March 24, 2026 updated by: Dr. Albert Kar-Kin Chung, The University of Hong Kong

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Actual)

110

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Hong Kong
      • Hong Kong, Hong Kong, 000000
        • Queen Mary Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

16 years to 60 years (Child, Adult)

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

16-60 years old cannabis users

Description

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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
18 months
Frontal Assessment Battery
Time Frame: 18 months
Subject who scores 12 or below will be considered having frontal dysexcutive function
18 months
Wechsler Memory Scale
Time Frame: 18 months
Subject will be assessed with the scale for their immediate, delayed, visual and auditory memory
18 months
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
Each subject only need to have venous blood test once 1 day within their 18-months study period

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

The University of Hong Kong

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 1, 2020

Primary Completion (Actual)

August 31, 2025

Study Completion (Actual)

December 31, 2025

Study Registration Dates

First Submitted

April 23, 2020

First Submitted That Met QC Criteria

May 1, 2020

First Posted (Actual)

May 4, 2020

Study Record Updates

Last Update Posted (Actual)

March 27, 2026

Last Update Submitted That Met QC Criteria

March 24, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • UW 20-189

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

data without identifiable

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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