8.1 Mood Disorders (Depression, Bipolar) & Suicide Risk Assessment

8.1 Mood Disorders (Depression, Bipolar) & Suicide Risk Assessment

Mood disorders constitute one of the most common presentations in primary care and emergency departments across Canada. The Canadian Network for Mood and Anxiety Treatments (CANMAT) provides evidence-based guidelines for the diagnosis, pharmacotherapy, and management of Major Depressive Disorder (MDD) and Bipolar Disorder.

Major Depressive Disorder (MDD)

Diagnostic Criteria (DSM-5-TR)

A diagnosis of Major Depressive Disorder requires at least 5 of 9 symptoms present during the same 2-week period, representing a change from previous functioning. At least one of the symptoms must be depressed mood or anhedonia (loss of interest/pleasure).

The classic diagnostic mnemonic SIGECAPS summarizes the criteria:

• Sleep disturbances (insomnia or hypersomnia)
• Interest loss (anhedonia)
• Guilt or feelings of worthlessness
• Energy loss (fatigue)
• Concentration impairment or indecisiveness
• Appetite or weight changes (increase or decrease)
• Psychomotor agitation or retardation
• Suicidal ideation or recurrent thoughts of death

Initial Medical Workup

Before confirming MDD, physicians must rule out organic secondary causes of depressive symptoms. Standard screening investigations include:

• Thyroid Stimulating Hormone (TSH): Hypothyroidism frequently presents with fatigue, weight gain, and low mood.
• Complete Blood Count (CBC) & Vitamin B12 / Folate: Anemia and B12 deficiency cause severe cognitive slowing and fatigue.
• Serum Electrolytes, Renal, and Liver Function: Exclude metabolic encephalopathy or organ failure.
• Substance Screening: Exclude alcohol use disorder, cannabis overuse, or withdrawal from central nervous system stimulants.

CANMAT Guidelines for MDD Management

CANMAT categorizes pharmacotherapy into first-, second-, and third-line options based on efficacy, tolerability, and safety in overdose.

Clinical Scenario: A 34-year-old male presents with low mood, fatigue, anhedonia, and difficulty concentrating for 6 weeks following a job loss. He has no past history of mania or hypomania. He expresses worry about sexual dysfunction because a friend had issues on medication. What is the most appropriate initial antidepressant?
Answer: Bupropion is an ideal choice because as a Norepinephrine-Dopamine Reuptake Inhibitor (NDRI), it carries minimal risk of sexual dysfunction and weight gain.

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Bipolar Disorders

Bipolar disorders are characterized by pathologic mood swings ranging from severe depression to mania or hypomania.

Diagnostic Distinctions

• Bipolar I Disorder: Requires at least one manic episode (period of abnormally elevated, expansive, or irritable mood and abnormally increased activity/energy lasting $\ge 1$ week, or requiring hospitalization). Psychotic features may be present. Depressive episodes are common but not strictly required for diagnosis.
• Bipolar II Disorder: Requires at least one hypomanic episode ($\ge 4$ consecutive days, milder elevation without marked social/occupational impairment or psychotic features) AND at least one major depressive episode.
• Cyclothymic Disorder: Fluctuating hypomanic and depressive symptoms for $\ge 2$ years in adults ($\ge 1$ year in children) without meeting full criteria for major depressive or hypomanic episodes.

CANMAT Guidelines for Bipolar Disorder Pharmacotherapy

CRITICAL EXAM TRAP: Never prescribe antidepressant monotherapy in Bipolar I Disorder. Antidepressants can precipitate a manic switch, rapid cycling, or mixed states. Always ensure a stabilizing mood agent (lithium, divalproex, or atypical antipsychotic) is established first.

First-Line Treatments by Phase:

1. Acute Mania:
   • Monotherapy: Lithium, Divalproex (Valproic acid), Aripiprazole, Quetiapine, Risperidone, Asenapine.
   • Combination Therapy: Lithium or Divalproex + Atypical Antipsychotic (e.g., Quetiapine or Risperidone).
2. Acute Bipolar Depression:
   • Quetiapine, Lurasidone + Lithium/Divalproex, Lithium monotherapy, Lamotrigine.
3. Maintenance Phase:
   • Lithium (reduces suicide risk), Divalproex, Lamotrigine (prevents depressive relapses; watch for Stevens-Johnson Syndrome rash), Quetiapine, Aripiprazole.

Lithium Therapy & Toxicity Management

Lithium is a frontline mood stabilizer with proven anti-suicidal properties. However, it possesses a very narrow therapeutic index.

• Therapeutic Range: 0.6 – 1.2 mmol/L (acute mania: 0.8 – 1.2 mmol/L; maintenance: 0.6 – 0.8 mmol/L).
• Baseline Workup: Serum creatinine, eGFR, BUN, electrolytes, TSH, calcium, ECG, and pregnancy test ($\beta$-hCG).
• Adverse Effects: Tremor, hypothyroidism, nephrogenic diabetes insipidus (polyuria/polydipsia), weight gain, hyperparathyroidism/hypercalcemia. Teratogenic risk: Ebstein anomaly (congenital tricuspid valve displacement) if used in early pregnancy.
• Lithium Toxicity:
  • Mild-Moderate (1.5 – 2.0 mmol/L): Coarse tremor, dysarthria, ataxia, nausea, vomiting, diarrhea.
  • Severe (>2.0 – 2.5 mmol/L): Choreoathetosis, seizures, delirium, coma, cardiac arrhythmias.
  • Management: Stop lithium, aggressive IV hydration with normal saline. Hemodialysis is indicated if levels exceed 2.5 mmol/L with severe symptoms, or >4.0 mmol/L regardless of clinical status.

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Suicide Risk Assessment & Canadian Mental Health Law

Risk Stratification & SAD PERSONS Mnemonic

Evaluating suicide risk involves identifying risk factors, protective factors, and acute intent.

• Non-modifiable Risk Factors: Prior suicide attempt (single strongest predictor of future completed suicide), male sex, older age ($\ge 45$ or elderly), white or Indigenous ethnicity, family history of suicide.
• Modifiable Risk Factors: Active major depression, bipolar disorder, substance abuse/intoxication, access to lethal means (firearms, prescription pills), loss of social support, severe chronic pain/illness.

SAD PERSONS Mnemonic:
S - Sex (Male)
A - Age (<19 or >45)
D - Depression / Diagnosis

P - Previous attempt
E - Ethanol / Substance use
R - Rational thinking loss (Psychosis)
S - Social support lacking
O - Organized plan
N - No spouse / Living alone
S - Sickness (Chronic illness)

Provincial Mental Health Legislation & Involuntary Admission

In Canada, psychiatric hold legislation is governed by provincial Mental Health Acts (e.g., Form 1 in Ontario, Form 22/10 in British Columbia, Form 1 in Alberta).

Criteria for Involuntary Psychiatric Assessment:

1. The person has a mental disorder.
2. The person is likely to cause harm to self, harm to others, or suffer severe physical impairment/deterioration.
3. The person is unsuitable for voluntary admission.

Exam Tip: Voluntary admission is preferred whenever possible. However, if a patient presents with imminent suicide intent, a high-lethality plan, and refuses voluntary admission, the physician has a legal and ethical duty of care to issue an involuntary assessment order (e.g., Form 1) to detain the patient for emergency evaluation (up to 72 hours in Ontario).