Change in Cognitive Function in Stimulant Users

Study Overview
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Brief Summary
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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.

Official Title
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A Prospective Study to Evaluate the Change in Cognitive Function in Stimulant Users

Conditions
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Cognitive Dysfunction, Stimulant Use, Methamphetamine Abuse, Cocaine Use, Substance Use

Intervention / Treatment
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* Behavioral: Cognitive Assessment


Participation Criteria
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Eligibility Criteria
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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. 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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Stimulant Users<br>Stimulant users that fulfill SCID-5 clinician version definition for assessment on stimulant use disorder under DSM-5 | Behavioral: Cognitive Assessment<br>* Assessment on cognitive dysfunction using standardised cognitive tests<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Montreal Cognitive Assessment | Measure the change in global cognitive function | 12 months | 
| Frontal Assessment Battery | Measure the change in executive function | 12 months | 
| Diagnostic and Statistical Manual of mental disorders 5th edition (DSM-5 )severity of stimulant use disorder | To determine different severity of stimulant use | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of stimulant use |  | 12 months |