Effects of Cannabis Abstinence on Symptoms and Cognition in Depression

Centre for Addiction and Mental Health19 enrolled

Overview

The objective of this study is to assess the changes in symptoms and cognition that occur after a 28-day abstinence period in patients with comorbid Cannabis Use Disorder (CUD) and Major Depression (MDD). This study employs a 28-day abstinence paradigm a total of 8 visits to the CAMH Russell site (screening, training, baseline, week 1, week 2, week 3, week 4, follow-up). Participants should be between the ages of 18-55, meet criteria for moderate depression and CUD, be non-treatment seeking, and be on a stable dose of antidepressant medication. The study visits will take up a total of approximately 22.5 hours with compensation for time provided. These visits will involve multiple clinical, substance use, and cognitive assessments. Abstinence will be maintained by weekly behavioural coaching sessions and contingency reinforcement.

Study Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Cannabis Use Disorder Major Depressive Disorder Cognition

Weekly Behavioral Coaching SessionBEHAVIORAL

The participants will be provided with a 20-minute individual behavioral support session weekly for 4 weeks (28 days of abstinence), designed to provide them with tools and techniques to manage the craving and withdrawal symptoms that occur with cessation.

Contingency ManagementBEHAVIORAL

If the participant's weekly abstinence is successful as determined by the urine results on day 28, the participant will receive an additional $300.00 cash bonus on top of their hourly $10 compensation for attending all visits. We predict that this cash bonus is enough incentive to allow for the behavioural change of abstinence in this patient population.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 55 Years

Medical Language ↔ Plain English

Inclusion Criteria: * ages 18-55 * meet DSM-5 diagnostic criteria for cannabis use disorder (cannabis use \>1 g/day, CUDIT score \>12) * meet DSM-5 diagnostic criteria for Major Depressive Disorder as determined using the SCID * be an outpatient receiving a stable dose of antidepressant medication(s) for at least 1 month * have a Hamilton Depression Rating Scale (HDRS-17) baseline total score greater than 14 * have a Full Scale IQ greater than 80 as determined by the WTAR * be a non-treatment seeking cannabis user * evidence of sufficient motivation and effort as measure by a Test of Memory Malingering (TOMM) score greater than 45 * urinary baseline THC-COOH levels greater than 150 ng/ml Exclusion Criteria: * meets criteria for abuse or dependence of alcohol or other illicit substances within the part 6 months (with the exception of cannabis, nicotine, or caffeine) * positive urine screen for illicit substances other than cannabis, nicotine or caffeine * current suicidal or homicidal ideation * psychotic disorder diagnosis (e.g. schizoaffective disorder, major depression with psychotic features) as determined by the SCID * head injury with loss of consciousness greater than 2 minutes or requiring hospitalization * neurological or medical condition determined to effect cognition * be treatment seeking for cannabis use

Outcomes

Primary Outcomes

The effects of 28 day cannabis abstinence on change in depressive symptoms in cannabis-dependent patients with Major Depressive Disorder (MDD) as assessed by the Hamilton Rating Scale for Depression (HRSD).

The clinical assessment will be administered weekly during the abstinence period and conducted by study personnel. The HRDS is used to evaluate depression on a 17-item scale with higher values indicating worse depressive symptoms.

Time frame: Weekly (Day 0, Day 7, Day 14, Day 21, Day 28) and at 8 weeks (Follow-up Day 56)

Secondary Outcomes

The effects of 28 day cannabis abstinence on change in cognitive function in cannabis dependent patients with Major Depressive Disorder (MDD) as assessed by a cognitive battery administered at Baseline, Week 2, Endpoint and Follow-Up.

The cognitive battery will include the primary outcome of verbal memory (assessed by Hopkins Verbal Learning Test) and will be compared to baseline (Day 1) performance. Cortical inhibition will also be assessed and compared.

Time frame: Bi-Weekly (Day 0, Day 14, Day 28) and at 8 Weeks (Follow-up Day 56)

The effects of 28 day cannabis abstinence on change in co-occurring anxiety in cannabis dependent patients with MDD as assessed by the Beck Anxiety Inventory (BAI) administered weekly.

The clinical assessment will be administered at Baseline, weekly during the abstinence period and Follow-up and will be conducted by study personnel. The BAI is a 21-item scale used to evaluate the severity of anxiety symptoms with higher values indicating worse outcomes.