Effects of THC on Emotional Memory Retrieval

Study Overview
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Brief Summary
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The main purpose of this study was to examine the effects of THC on the retrieval of emotional and neutral memories in healthy young adults. Secondary experiments included the effects of THC on the encoding of object and scene stimuli and a novel working memory task.

Detailed Description
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Here, the investigators aimed to investigate the effects of THC (15 mg) on the retrieval of negative, neutral, and positive memories. The study used a placebo-controlled, within-subjects, crossover design with 24 participants. In each experimental arm, participants attend a session to encode stimuli, a second session 48 hours later in which their memories are tested for the stimuli from the first session followed by the encoding of object-scene stimuli and a working memory test, and a third session 48 hours later in which memory for the object-scene stimuli is tested. In the second session, two hours prior to memory testing, THC or placebo is administered. On the first and second sessions subjects complete mood questionnaires.

Official Title
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The Effects of Δ⁹-Tetrahydrocannabinol on the Retrieval of Emotional Memories

Conditions
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Healthy

Intervention / Treatment
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* Drug: THC
* Drug: Placebo oral capsule


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 4-100 lifetime cannabis occasions Exclusion Criteria: Current Axis I DSM-IV disorder, including substance dependence, current use of >5 cigarettes per day, history of psychosis or mania, less than a high school education, lack of English fluency, a body mass index outside 19-33 kg/m2, high blood pressure (>140/90), abnormal electrocardiogram, daily use of any medication other than birth control, pregnancy, or lactating.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Half of the participants will receive placebo during the second session in the first experimental arm and THC during the second session in the second experimental arm. The other half of participants will receive THC during the second session in the first experimental arm and placebo during the second session in the second experimental arm.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Placebo oral capsule<br>Participants came in for the first session that involved encoding emotional pictures and lists of semantically related words (Deese-Roediger-McDermott or DRM task; a false memory task). Forty-eight hours later, participants received a placebo capsule (dextrose) and waited 2 hours Participants were monitored for the next 2 hours including physiological and subjective measures every 30 minutes. After 2 hours, participants' memory for the emotional stimuli and DRM stimuli was tested. Participants then encoded object stimuli overlaid onto scenes followed by a working memory test with simple color squares. After the memory tests and 3.5 hours post-capsule, if participants' physiological and subjective measures had returned to baseline, they were allowed to leave. Forty-eight hours later, memory for the object-scene stimuli was tested. Other than the capsule, this arm was identical to the THC arm. | Drug: Placebo oral capsule<br>* A capsule that contains only dextrose filler administered 2 hours prior to memory testing.<br>* Other names: Dextrose;|
| Experimental: THC<br>Participants came in for the first session that involved encoding emotional pictures and lists of semantically related words (Deese-Roediger-McDermott or DRM task; a false memory task). Forty-eight hours later, participants received a placebo capsule (dextrose) and waited 2 hours Participants were monitored for the next 2 hours including physiological and subjective measures every 30 minutes. After 2 hours, participants' memory for the emotional stimuli and DRM stimuli was tested. Participants then encoded object stimuli overlaid onto scenes followed by a working memory test with simple color squares. After the memory tests and 3.5 hours post-capsule, if participants' physiological and subjective measures had returned to baseline, they were allowed to leave. Forty-eight hours later, memory for the object-scene stimuli was tested. Other than the capsule, this arm was identical to the placebo arm. | Drug: THC<br>* A capsule that contains 15 mg of THC as well as dextrose filler administered 2 hours prior to memory testing.<br>* Other names: Marinol;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Emotional Memory | Hit and false alarm rates for negative, neutral, and positive picture stimuli | Two hours after placebo/THC administration. | 
| DRM Memory | Hit and false alarm rates for the DRM task | Two and a half hours after placebo/THC administration. | 
| Object Memory | Hit and false alarm rates for object stimuli on the same or different encoding scenes | 48 hours after placebo/THC administration. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Addiction Research Centre Inventory Marijuana Scale | The Addiction Research Centre Inventory (ARCI; Martin, Sloan, Sapira, & Jasinski, 1971) measures drug-specific effects on a 56-item true-false questionnaire. For this study, the investigators report the composite score of 12 questions that make up the marijuana scale (Chait, Fischman, & Schuster, 1985). | Assessed just prior to placebo/THC administration and then 30 minutes, 60 minutes, 90 minutes, and 115 minutes after placebo/THC administration. | 
| Visual Analog Scales | The Visual Analog Scales (VAS; Folstein & Luria, 1973) is composed of thirteen adjectives used to assess individual dimensions of subjective mood - anxious, stimulated, sedated, elated, insightful, sociable, confident, lonely, playful, dizzy, loving, friendly, and restless, rated on a sliding scale from 'not at all' to 'extremely.' | Assessed just prior to placebo/THC administration and then 30 minutes, 60 minutes, 90 minutes, and 115 minutes after placebo/THC administration. | 
| Drug Effects Questionnaire | The Drug Effects Questionnaire (DEQ; Morean et al., 2013) is composed of five questions concerning current drug effects - how much participants feel a drug effect, like the effect, dislike the effect, feel high, and want more of the drug, rated on a sliding scale from 'not at all/neutral' to 'very much.' | Assessed just prior to placebo/THC administration and then 30 minutes, 60 minutes, 90 minutes, and 115 minutes after placebo/THC administration. | 
| Physiological Measure 1 | Heart rate | Assessed just prior to placebo/THC administration and then 30 minutes, 60 minutes, 90 minutes, and 115 minutes after placebo/THC administration. | 
| Physiological Measure 2 | Blood pressure | Assessed just prior to placebo/THC administration and then 30 minutes, 60 minutes, 90 minutes, and 115 minutes after placebo/THC administration. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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THC, adult