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Substance Use Or Addictive Disorders

Introduction to Addiction Psychiatry for MCCQE1

Substance Use Disorders (SUD) represent a significant portion of the MCCQE1 psychiatry and population health objectives. As a future Canadian physician, understanding the nuances of addiction medicine is crucial, not only for the exam but for daily practice under the CanMEDS roles of Medical Expert, Communicator, and Health Advocate.

In the DSM-5, the distinction between “abuse” and “dependence” has been replaced by a single continuum of Substance Use Disorder, measured from mild to severe.

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Canadian Context: Canada is currently facing a significant public health crisis regarding opioid-related overdoses and deaths. Understanding Harm Reduction strategies is a high-yield topic for the MCCQE1.

DSM-5 Diagnostic Criteria

Diagnosis is based on a pathological pattern of behaviors related to the use of the substance. To diagnose a SUD, at least 2 of the following 11 criteria must be met within a 12-month period.

Mnemonic: The 11 Criteria (Grouped)

To help with MCCQE1 preparation, group the symptoms into four categories: Impaired Control, Social Impairment, Risky Use, and Pharmacological Criteria.

The 4 Categories of SUD

1. Impaired Control

  • Taking larger amounts than intended
  • Unsuccessful efforts to cut down
  • Time spent obtaining/using/recovering
  • Craving

2. Social Impairment

  • Failure to fulfill major obligations
  • Continued use despite social problems
  • Giving up activities

3. Risky Use

  • Use in hazardous situations
  • Use despite physical/psychological problems

4. Pharmacological

  • Tolerance
  • Withdrawal

Severity Specifiers:

  • Mild: 2–3 symptoms
  • Moderate: 4–5 symptoms
  • Severe: 6 or more symptoms

Screening Tools

Screening is a vital skill for the MCCQE1. You must choose the appropriate tool for the patient profile.

CAGE Questionnaire (High specificity, lower sensitivity than AUDIT). A score of ≥ 2 suggests alcohol misuse.

  1. Have you ever felt you should Cut down on your drinking?
  2. Have people Annoyed you by criticizing your drinking?
  3. Have you ever felt bad or Guilty about your drinking?
  4. Have you ever had a drink first thing in the morning to steady your nerves (Eye-opener)?

Alcohol Use Disorder (AUD)

Alcohol is the most common substance of abuse in Canada.

Alcohol Withdrawal

Withdrawal can be life-threatening. The timeline is critical for MCCQE1 clinical reasoning.

Time Since Last DrinkSymptomsPathophysiology
6–12 HoursMinor withdrawal: Insomnia, tremulousness, mild anxiety, GI upset, headache, palpitations.Autonomic hyperactivity
12–24 HoursAlcoholic Hallucinosis: Visual, auditory, or tactile hallucinations. Patient usually retains intact sensorium (aware they are hallucinating).Dopaminergic excess
12–48 HoursWithdrawal Seizures: Generalized tonic-clonic. Usually singular or a short burst.Glutamate rebound / GABA deficiency
48–96 HoursDelirium Tremens (DTs): Agitation, global confusion, disorientation, hallucinations, fever, autonomic hyperactivity (tachycardia, hypertension). Medical Emergency.Severe GABA deficiency / NMDA excitation

Management of AUD

1. Acute Withdrawal Management

  • Assessment: Use the CIWA-Ar (Clinical Institute Withdrawal Assessment for Alcohol, revised) scale to guide treatment.
  • Pharmacotherapy: Benzodiazepines (Diazepam, Lorazepam, Chlordiazepoxide).
    • Symptom-triggered dosing is preferred over fixed-schedule dosing in Canada to reduce total drug administration and duration of treatment.
    • Liver Disease: Use Lorazepam or Oxazepam (metabolized by glucuronidation, bypassing Phase I oxidation). Mnemonic: OTL (Outside The Liver).
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Wernicke’s Encephalopathy Prophylaxis: Always administer Thiamine (Vitamin B1) before or with glucose to prevent precipitation of Wernicke’s Encephalopathy (Confusion, Ataxia, Ophthalmoplegia).

2. Long-term Pharmacotherapy (Relapse Prevention)

Current Canadian guidelines suggest offering pharmacotherapy to patients with moderate-to-severe AUD.

  • Naltrexone: Opioid antagonist. Reduces cravings and the “high” from alcohol. First-line. Contraindicated in acute hepatitis or liver failure.
  • Acamprosate: NMDA receptor antagonist/GABA agonist. Maintains abstinence. Safe in liver disease; renal dose adjustment required.
  • Disulfiram: Inhibits aldehyde dehydrogenase. Causes severe reaction if alcohol is consumed. Second-line; requires high motivation.

Opioid Use Disorder (OUD)

Given the Canadian Opioid Crisis, this is a critical topic for the MCCQE1.

Clinical Presentation

  • Intoxication: Euphoria, apathy, dysphoria, psychomotor agitation/retardation, impaired judgment.
  • Overdose Triad:
    1. Coma (Unconsciousness)
    2. Pinpoint Pupils (Miosis)
    3. Respiratory Depression (RR < 12)

Management

Step 1: Emergency Management (Overdose)

Secure ABCs. Administer Naloxone (Opioid antagonist). It can be given IV, IM, SC, or intranasally. Observe for “re-narcotization” as Naloxone has a shorter half-life than many opioids.

Step 2: Withdrawal Management

Opioid withdrawal is extremely uncomfortable but rarely life-threatening (unlike alcohol).

  • Symptoms: Nausea, vomiting, diarrhea, muscle aches, lacrimation, rhinorrhea, pupillary dilation, piloerection (“gooseflesh”), yawning.
  • Assessment: COWS (Clinical Opiate Withdrawal Scale).
  • Treatment: Clonidine (alpha-2 agonist), NSAIDs, anti-emetics, loperamide.

Step 3: Opioid Agonist Therapy (OAT)

Long-term management is the standard of care in Canada to reduce mortality and illicit use.

Canadian Guidelines for OAT

According to CRISM (Canadian Research Initiative in Substance Misuse) guidelines:

  1. Buprenorphine/Naloxone (Suboxone): First-line treatment.
    • Partial agonist (high affinity, low intrinsic activity).
    • Safer profile (ceiling effect on respiratory depression).
    • Can be prescribed by primary care physicians (varies by province, but generally accessible).
  2. Methadone: Second-line (or first-line if Suboxone is contraindicated/failed).
    • Full agonist.
    • Higher risk of QT prolongation and overdose.
    • Requires special exemption/training to prescribe in many jurisdictions.
  3. Slow-Release Oral Morphine (SROM): Third-line for refractory cases.

Stages of Change (Transtheoretical Model)

Understanding where a patient is in their journey is vital for the Communicator role in MCCQE1.

  1. Pre-contemplation: Not considering change. (“I don’t have a problem.”)
  2. Contemplation: Ambivalent about change. (“I know it’s bad, but it helps me relax.”)
  3. Preparation: Planning to change. (“I’ve looked up AA meeting times.”)
  4. Action: Actively changing behavior. (Attending meetings, abstaining).
  5. Maintenance: Sustained change for > 6 months.
  6. Relapse: Return to old behaviors (Part of the cycle, not a failure).

Motivational Interviewing (MI)

Use the OARS mnemonic for counselling:

  • Open-ended questions
  • Affirmations
  • Reflective listening
  • Summaries

Canadian Guidelines & Public Health

Canada’s Guidance on Alcohol and Health (2023)

The CCSA (Canadian Centre on Substance Use and Addiction) released updated guidelines representing a paradigm shift:

  • 0 drinks per week: Not drinking has benefits, such as better health and better sleep.
  • 2 standard drinks or less per week: You are likely to avoid alcohol-related consequences for yourself or others.
  • 3–6 standard drinks per week: Your risk of developing several types of cancer, including breast and colon cancer, increases.
  • 7 or more standard drinks per week: Your risk of heart disease or stroke increases significantly.

Harm Reduction

This is a cornerstone of Canadian addiction medicine. Examples include:

  • Supervised Consumption Sites (SCS).
  • Needle Exchange Programs (prevent HIV, Hep C).
  • Take-home Naloxone kits.
  • Managed Alcohol Programs (MAPs).

Key Points to Remember for MCCQE1

  • Priority: Always rule out life-threatening withdrawal (Alcohol/Benzos) or overdose (Opioids) first.
  • Safety: In an agitated patient, verbal de-escalation is the first step. If pharmacological restraint is needed, antipsychotics (e.g., Haloperidol) or benzos (e.g., Lorazepam) are used.
  • Dual Diagnosis: Concurrent disorders (SUD + Mental Illness) are the rule, not the exception. Treat both simultaneously.
  • Special Populations:
    • Pregnancy: Opioid withdrawal can cause fetal demise. OAT (Methadone or Buprenorphine) is preferred over medically supervised withdrawal.
    • Adolescents: Cannabis use is associated with an increased risk of developing psychotic disorders.

Sample Question

Clinical Scenario

A 48-year-old male presents to the emergency department accompanied by police. He was found confused in a public park. On examination, he is agitated, diaphoretic, and has a coarse tremor of his hands. His vital signs are: Temperature 38.1°C, Heart Rate 118 bpm, Blood Pressure 158/96 mmHg, Respiratory Rate 22/min. He is disoriented to time and place. He has a history of alcohol use disorder but has not consumed alcohol for approximately 3 days due to financial difficulties.

Which of the following is the most appropriate initial pharmacological management?

  • A. Haloperidol
  • B. Phenytoin
  • C. Lorazepam
  • D. Carbamazepine
  • E. Disulfiram

Explanation

The correct answer is:

  • C. Lorazepam

Explanation: This patient is presenting with signs and symptoms consistent with Delirium Tremens (DTs), the most severe form of alcohol withdrawal. The clinical features include autonomic hyperactivity (tachycardia, hypertension, fever, diaphoresis), agitation, and global confusion (delirium) occurring 48–96 hours after cessation of alcohol.

  • Option C (Lorazepam): Benzodiazepines are the cornerstone of therapy for alcohol withdrawal and DTs. They act by enhancing GABA activity, compensating for the GABA deficiency caused by chronic alcohol use. Lorazepam is an excellent choice, particularly if liver function is unknown or compromised, as it does not require hepatic oxidation.
  • Option A (Haloperidol): Antipsychotics lower the seizure threshold and can worsen the autonomic instability in DTs. They may be used as an adjunct for severe agitation but never as monotherapy.
  • Option B (Phenytoin): Anticonvulsants like phenytoin are ineffective in preventing or treating alcohol withdrawal seizures.
  • Option D (Carbamazepine): While carbamazepine can be used for mild-to-moderate withdrawal management in an outpatient setting, it is not suitable for the acute management of Delirium Tremens in the emergency department.
  • Option E (Disulfiram): This is an aversion therapy used for relapse prevention in stable, abstinent patients. It has no role in the acute management of withdrawal.

Key Takeaway: Benzodiazepines are the first-line treatment for alcohol withdrawal delirium.

References

  1. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing.
  2. Bruneau, J., et al. (2018). Management of opioid use disorders: a national clinical practice guideline. CMAJ, 190(9), E247-E257. [CRISM Guidelines]
  3. Canadian Centre on Substance Use and Addiction (CCSA). (2023). Canada’s Guidance on Alcohol and Health: Final Report.
  4. Centre for Addiction and Mental Health (CAMH). (n.d.). Alcohol Withdrawal Management.
  5. Medical Council of Canada. (n.d.). MCCQE Part I Clinical Decision-Making and Multiple-Choice Question Objectives.
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