Change in Cognitive Function in Stimulant Users (SToP-S_CogFx)
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ClinicalTrials.gov Identifier: NCT04061941 |
Recruitment Status :
Recruiting
First Posted : August 20, 2019
Last Update Posted : November 23, 2021
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In Hong Kong, methamphetamine use is common and cocaine use has increased steadily over the past few years. While the use of ketamine decreased from 35.8% in 2015 to 13.9% in 2017, methamphetamine and cocaine have become the most commonly used psychotropic substances and account for more than 50% of drug abuses cases in 2017. Among all stimulants, methamphetamine is most commonly used because it releases three times more dopamine than cocaine and the effects can last from eight to twelve hours, compared to two hours for cocaine. On top of its extreme effects, methamphetamine is relatively inexpensive, making it even more accessible to the young population.
Misuse of methamphetamine has long been associated with profound psychological and cognitive disturbance. In reviewing the cognitive data from reasonably well-matched groups of chronic methamphetamine users and healthy controls, the majority of studies have found that chronic methamphetamine users had lower scores on at least some cognitive tests, although some studies are exceptions with entirely nonsignificant differences. A meta-analysis of 17 cross-sectional studies found that chronic methamphetamine users demonstrated significantly lower cognitive scores than healthy controls. The effects were largest for measures of learning, executive functions, memory, and processing speed, although the majority of cognitive domains significantly differed between the groups.
Concerns has been emerging regarding the methodology of the aforementioned results. In particular, the appropriateness of using healthy controls to examine the cognitive effects of stimulant use has been questioned. Much of the published research has fallen victim to using controls with significant baseline differences from the chronic stimulant users, such as years of education. In addition, none of the studies available provided scatter plots of their cognitive data to evaluate the overlap in performance between chronic stimulant users and healthy controls. In fact, many chronic stimulant users have normal cognitive function when compared with normative data. Therefore, the use of the term 'impairment' or 'deficit' in many studies is not fully justified. Another limitation is that it cannot differentiate cognitive weaknesses that may predate stimulant use from those that result from it. Notably, longitudinal studies have shown that childhood deficits in executive function can predict drug abuse in adolescence, suggesting that at least some of the cognitive weaknesses pre-exist in chronic stimulant user. These and other limitations provoked a conclusion that the evidence for cognitive deficits in chronic stimulant users is weak.
In order to overcome the methodological issues observed in previous cross-sectional studies, we propose to conduct a prospective studies to determine the change in cognitive function among stimulant users over time.
Condition or disease | Intervention/treatment |
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Cognitive Dysfunction Stimulant Use Methamphetamine Abuse Cocaine Use Substance Use | Behavioral: Cognitive Assessment |
Study Type : | Observational |
Estimated Enrollment : | 120 participants |
Observational Model: | Cohort |
Time Perspective: | Prospective |
Official Title: | A Prospective Study to Evaluate the Change in Cognitive Function in Stimulant Users |
Actual Study Start Date : | October 21, 2019 |
Estimated Primary Completion Date : | December 31, 2022 |
Estimated Study Completion Date : | December 31, 2023 |
Group/Cohort | Intervention/treatment |
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Stimulant Users
Stimulant users that fulfill SCID-5 clinician version definition for assessment on stimulant use disorder under DSM-5
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Behavioral: Cognitive Assessment
Assessment on cognitive dysfunction using standardised cognitive tests |
- Montreal Cognitive Assessment [ Time Frame: 12 months ]Measure the change in global cognitive function
- Frontal Assessment Battery [ Time Frame: 12 months ]Measure the change in executive function
- Diagnostic and Statistical Manual of mental disorders 5th edition (DSM-5 )severity of stimulant use disorder [ Time Frame: 12 months ]To determine different severity of stimulant use
- Frequency of stimulant use [ Time Frame: 12 months ]

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Ages Eligible for Study: | 18 Years to 65 Years (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Sampling Method: | Non-Probability Sample |
Inclusion Criteria:
- Age: 18 - 65 years old at the time of enrolment
- Able to read and communicate in English and/or Chinese
- Able to give informed consent
- Using stimulants as the primary psychoactive substance of abuse
- "Repeated" and "Active" stimulant users as defined by Structured Clinical Interview for DSM-5 Disorders (SCID-5)
Exclusion Criteria:
- Age <18 years old
- Unable to read English or Chinese
- Unable to give informed consent
- Had been diagnosed with other Substance Use or Related Disorders with severity ≥4 according to DSM-5, or other psychoactive substance dependence syndrome according to International Classification of Disease (ICD-10)
- Currently taking regular prescribed psychiatric medications, including antipsychotics, antidepressants, mood stabilizers, anti-epileptics, benzodiazepines, hypnotics, and anti-cholinergic medications.
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Had been diagnosed with other DSM-5 disorders including:
- Neurodevelopmental Disorders
- Schizophrenia Spectrum and Other Psychotic Disorders
- Bipolar and Related Disorders
- Depressive Disorders, Anxiety Disorders, and Obsessive-Compulsive and Related Disorders
- Dissociative Disorders, Somatic Symptoms and Related Disorders
- Feeding and Eating Disorders
- Sleep-wake Disorders
- Neurocognitive Disorders

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04061941
Contact: albert KK Chung, MBBS(HK) | 2255 4486 | chungkka@hku.hk |
Hong Kong | |
Queen Mary Hospital | Recruiting |
Hong Kong, Hong Kong, 000000 | |
Contact: Albert KK Chung |
Responsible Party: | Dr. Albert Kar-Kin Chung, Clinical Assistant Professor, The University of Hong Kong |
ClinicalTrials.gov Identifier: | NCT04061941 |
Other Study ID Numbers: |
BDF180058 |
First Posted: | August 20, 2019 Key Record Dates |
Last Update Posted: | November 23, 2021 |
Last Verified: | November 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
Substance-Related Disorders Cognitive Dysfunction Chemically-Induced Disorders |
Mental Disorders Cognition Disorders Neurocognitive Disorders |