📋 Key Information Summary
- DSM-5 classifies depressive disorders as major depressive disorder (MDD), persistent depressive disorder (dysthymia), disruptive mood dysregulation disorder, premenstrual dysphoric disorder, and substance/medication-induced depressive disorder — each with specific diagnostic criteria and duration thresholds.
- Severity grading (mild, moderate, severe) is based on symptom count, functional impairment, and the presence of psychotic or melancholic features; severity dictates treatment intensity and setting.
- First-line pharmacotherapy for MDD in Australian general practice is an SSRI (e.g., sertraline, escitalopram) — all PBS-listed as General Benefits — combined with psychotherapy (CBT, IPT) for moderate-to-severe disease.
- Bipolar disorder (BD-I, BD-II, cyclothymia) must be distinguished from unipolar depression; misdiagnosis leads to antidepressant monotherapy, which risks manic switch. Mood stabilisers (lithium, valproate, lamotrigine) are the cornerstone of treatment.
- Lithium remains first-line for BD-I maintenance; monitor serum levels (0.4–0.8 mmol/L for maintenance), renal function (eGFR), thyroid function (TSH), and calcium every 3–6 months once stabilised.
- Perinatal depression affects ~1 in 7 Australian women; Edinburgh Postnatal Depression Scale (EPDS ≥13) is the recommended screening tool at 6–12 weeks postpartum and again at 6–12 months.
- Sertraline is the preferred SSRI in breastfeeding (lowest infant plasma levels); avoid doxepin and lithium monotherapy in breastfeeding mothers.
- Postnatal psychosis is a psychiatric emergency presenting within the first 2 weeks postpartum; requires immediate hospital admission, often under a Mother–Baby Unit.
- Suicide risk assessment is mandatory at every consultation; use the Columbia-Suicide Severity Rating Scale (C-SSRS) or equivalent, and develop a safety plan. In crisis, contact Lifeline 13 11 14 or 000.
- Aboriginal and Torres Strait Islander communities experience depression at 2–3 times the general population rate; culturally safe, trauma-informed care through ACCHOs and yarning-based approaches improves engagement.
- Social determinants — housing, incarceration, grief, racism, Stolen Generations — must be addressed alongside pharmacotherapy; referral to social and emotional wellbeing (SEW) programs is essential.
- Stepped care model (Australian Government Better Access): Step 1 (watchful waiting), Step 2 (low-intensity CBT, e.g., MindSpot, THIS WAY UP), Step 3 (face-to-face psychotherapy), Step 4 (specialist/complex care).
Introduction & Australian Epidemiology
Mood disorders — encompassing depressive disorders, bipolar disorders, and related conditions — are among the most common presentations in Australian general practice. They are the leading cause of non-fatal disease burden globally and contribute substantially to disability, lost productivity, and suicide.
In Australia, approximately 1 in 5 adults (4.2 million people) experienced a mental disorder in the past 12 months (2020–22 National Study of Mental Health and Wellbeing), with depressive episodes and anxiety disorders the most prevalent. Lifetime prevalence of major depressive disorder (MDD) in Australia is estimated at 10–15%, while bipolar disorder affects approximately 1.8–2.4% of the population (BD-I ~1%, BD-II ~0.8–1.1%).
Mood disorders disproportionately affect Aboriginal and Torres Strait Islander peoples, people in rural and remote areas, those experiencing socioeconomic disadvantage, and individuals with comorbid chronic disease. General practitioners (GPs) are the primary point of contact for the majority of Australians with mood disorders, and the gateway to the Better Access to Psychiatrists, Psychologists and General Practitioners through the MBS (Medicare Benefits Schedule) initiative.
Australian Burden of Disease
| Metric | Value (Australia) | Source |
|---|---|---|
| 12-month prevalence — any affective disorder | 6.2% (~1.3 million) | ABS NSMHW 2020–22 |
| Lifetime prevalence — MDD | 10–15% | AIHW 2023 |
| Lifetime prevalence — bipolar disorder | 1.8–2.4% | Mitchell et al., 2011 |
| Perinatal depression prevalence | ~1 in 7 women (~14%) | COPE / PANDA |
| Deaths by suicide (2023) | 3,214 (age-standardised rate 12.3 per 100,000) | ABS Causes of Death 2023 |
| Proportion of suicide deaths with mood disorder | ~40–60% | AIHW 2023 |
DSM-5 Classification & Severity Grading
The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, Text Revision (DSM-5-TR, 2022) classifies mood disorders into two broad groups: depressive disorders and bipolar and related disorders. This represents a major change from DSM-IV, which grouped them together as "mood disorders."
DSM-5 Depressive Disorders
| Disorder | Key Diagnostic Criteria | Duration |
|---|---|---|
| Major Depressive Disorder (MDD) | ≥5 of 9 SIG E CAPS symptoms (depressed mood or anhedonia mandatory); clinically significant distress or functional impairment | ≥2 weeks |
| Persistent Depressive Disorder (Dysthymia) | Depressed mood most days for ≥2 years (≥1 year in children/adolescents); ≥2 of: appetite change, sleep change, fatigue, low self-esteem, poor concentration, hopelessness | ≥2 years (no symptom-free period >2 months) |
| Disruptive Mood Dysregulation Disorder (DMDD) | Severe recurrent temper outbursts (verbal/behavioural) grossly out of proportion; irritable/angry mood between outbursts in ≥2 settings | ≥12 months (age 6–18 years) |
| Premenstrual Dysphoric Disorder (PMDD) | ≥5 of 11 symptoms (mood lability, irritability, depressed mood, anxiety, decreased interest, difficulty concentrating, fatigue, appetite change, sleep change, physical symptoms, anger); must include ≥1 core mood symptom | Last week of luteal phase; remit within days of menses onset; present in most menstrual cycles over past year |
| Substance/Medication-Induced Depressive Disorder | Prominent mood disturbance temporally related to substance/medication; not better explained by independent depressive disorder | During or shortly after intoxication/withdrawal/exposure |
| Depressive Disorder Due to Another Medical Condition | Prominent mood disturbance aetiologically related to a medical condition (e.g., hypothyroidism, Cushing's, multiple sclerosis, stroke) | Variable |
SIG E CAPS Mnemonic — 9 DSM-5 MDD Criteria
| Letter | Symptom | Notes |
|---|---|---|
| S | Sleep disturbance | Insomnia or hypersomnia |
| I | Interest loss (anhedonia) | Core criterion — must be present |
| G | Guilt (excessive/inappropriate) | Often nihilistic in melancholic depression |
| E | Energy loss / fatigue | Nearly universal |
| C | Concentration impaired | Must assess in context (elderly → screen for delirium/dementia) |
| A | Appetite/weight change | Increase or decrease ≥5% body weight in 1 month |
| P | Psychomotor changes | Agitation or retardation — observable by others |
| S | Suicidality / thoughts of death | Must be actively assessed at every contact |
Severity Grading — Clinical Guide
Types of Depressive Disorders
Major Depressive Disorder (MDD)
MDD is the most common depressive disorder seen in general practice. Diagnosis requires ≥5 of 9 SIG E CAPS symptoms during the same 2-week period, representing a change from previous functioning, with at least one symptom being depressed mood or anhedonia.
Exclusion Criteria
- Not attributable to the physiological effects of a substance or another medical condition (check thyroid, B12, folate, iron studies, cortisol)
- Not better explained by schizoaffective disorder, schizophrenia, schizophreniform disorder, delusional disorder, or other psychotic disorders
- No history of manic or hypomanic episodes (if present → bipolar disorder)
Persistent Depressive Disorder (Dysthymia)
Chronic low-grade depression lasting ≥2 years (≥1 year in children/adolescents). Many patients with persistent depressive disorder will have a superimposed MDD episode ("double depression"), which carries a worse prognosis. Treatment typically requires longer courses of antidepressant therapy and sustained psychotherapy.
Premenstrual Dysphoric Disorder (PMDD)
Affects 3–8% of menstruating women. Symptoms are confined to the late luteal phase and resolve within days of menses onset. First-line treatment is an SSRI — either continuously or luteal-phase-only dosing (e.g., fluoxetine 20 mg daily from day 14 to menses). Combined oral contraceptives containing drospirenone (e.g., Yaz®) are second-line.
Depressive Disorder Due to Another Medical Condition
Always exclude underlying medical causes before diagnosing a primary depressive disorder. Key conditions to screen:
| Medical Condition | Screening Investigation | MBS Item |
|---|---|---|
| Hypothyroidism | TSH ± free T4 | 66721 |
| Iron deficiency | FBC, ferritin, iron studies | 66555 |
| Vitamin B12 / folate deficiency | Serum B12, folate, homocysteine | 66841 / 66847 |
| Cushing's syndrome | 24-hr urinary cortisol or overnight dexamethasone suppression test | 66621 |
| Multiple sclerosis | MRI brain (if neurological signs present) | 63001 |
| Stroke / vascular disease | Clinical history, CT/MRI | 63001 |
| Medication-induced (corticosteroids, beta-blockers, interferons, hormonal agents) | Medication review | N/A |
Pharmacotherapy — Depressive Disorders
First-Line: SSRIs
Second-Line: SNRIs
Third-Line / Adjunct Agents
Non-Pharmacological Therapies
- Cognitive Behavioural Therapy (CBT): First-line psychotherapy for mild-to-moderate MDD; ≥12 sessions typically required. Available via Better Access MBS items (up to 10 individual + 10 group sessions per calendar year, with GP Mental Health Treatment Plan — MBS item 2710/2712).
- Interpersonal Therapy (IPT): Evidence-based for MDD, particularly effective in perinatal depression; focuses on role disputes, role transitions, grief.
- Behavioural Activation: Structured re-engagement with rewarding activities; effective as standalone for mild–moderate depression.
- Internet-based CBT (iCBT): MindSpot (free, government-funded), THIS WAY UP (low-cost), eCentreClinic — suitable for mild-to-moderate depression as Step 2 of stepped care.
- Electroconvulsive Therapy (ECT): Most effective treatment for severe, treatment-resistant, or psychotic depression; requires specialist referral; available in public and private psychiatric facilities across Australia.
Treatment-Resistant Depression
Defined as failure to achieve remission after ≥2 adequate trials of antidepressants (adequate dose and duration of 6–8 weeks). Management steps:
- Confirm diagnosis (exclude bipolar disorder, medical causes, substance use, personality factors)
- Optimise dose and ensure adherence (check for non-compliance, side effects, drug interactions)
- Switch to an antidepressant from a different class (e.g., SSRI → SNRI or mirtazapine)
- Augment with lithium (250–500 mg nocte, target serum level 0.4–0.8 mmol/L), thyroid hormone (T3, liothyronine 20–25 mcg/day), or an atypical antipsychotic (aripiprazole 2–5 mg/day — PBS authority for augmentation)
- Combine psychotherapy if not already engaged
- Refer for specialist review — consider ECT, repetitive transcranial magnetic stimulation (rTMS), or ketamine/esketamine (Spravato® — TGA-approved, specialist use only)
Bipolar Disorder
Bipolar disorder is a chronic, relapsing condition characterised by episodes of mania (BD-I), hypomania (BD-II), and depression. It is frequently misdiagnosed as unipolar depression, with an average diagnostic delay of 5–10 years in Australia.
DSM-5 Bipolar Classification
| Disorder | Key Features | Minimum Duration |
|---|---|---|
| Bipolar I Disorder | ≥1 manic episode (elevated/irritable mood + ≥3 DIGFAST symptoms); may have depressive and hypomanic episodes; hospitalisation usually required for mania | Mania: ≥7 days (or any duration if hospitalised) |
| Bipolar II Disorder | ≥1 hypomanic episode + ≥1 MDD episode; NO full manic episodes; hypomania causes observable change but no marked impairment/hospitalisation | Hypomania: ≥4 consecutive days; MDD: ≥2 weeks |
| Cyclothymic Disorder | Chronic fluctuating mood with hypomanic and depressive symptoms that do not meet criteria for hypomania or MDD | ≥2 years (≥1 year in children/adolescents) |
DIGFAST Mnemonic — Manic Episode Criteria
| Letter | Symptom |
|---|---|
| D | Distractibility |
| I | Impulsivity / Indiscretion (spending, sex, business decisions) |
| G | Grandiosity (inflated self-esteem, delusional) |
| A | Activity/energy increase (goal-directed, agitation) |
| S | Sleep deficit (feels rested after <3 hours) |
| T | Talkativeness / pressured speech |
Pharmacotherapy — Bipolar Disorder
Acute Mania
Maintenance / Prophylaxis
Lithium is first-line for maintenance prophylaxis in BD-I (reduces manic and depressive relapse by ~40–50%). Alternatives include lamotrigine (superior for bipolar depression prophylaxis), valproate, and quetiapine. Long-acting injectable antipsychotics (e.g., aripiprazole lauroxil) may be considered for adherence-challenged patients.
Perinatal Depression
The perinatal period — from conception to 12 months postpartum — is a time of elevated risk for mood disorders. In Australia, approximately 1 in 7 women (14%) experience perinatal depression, and 1 in 10 experience perinatal anxiety. Paternal perinatal depression affects approximately 1 in 10 new fathers. The condition is associated with adverse maternal, infant, and family outcomes if untreated.
Classification of Perinatal Mood Disorders
- Affects 50–80% of postpartum women
- Onset: Day 3–5 postpartum, peaks Day 5, resolves by Day 10–14
- Symptoms: mood lability, tearfulness, irritability, anxiety, fatigue
- No functional impairment; does not require pharmacological treatment
- Management: reassurance, psychoeducation, social support, sleep hygiene, peer support
- Affects ~14% of women during pregnancy or within 12 months postpartum
- Risk factors: prior depression, lack of social support, unplanned pregnancy, domestic violence, financial stress, migrant/refugee status, Aboriginal and Torres Strait Islander background, history of childhood adversity
- Symptoms: low mood, anhedonia, guilt, fatigue, sleep disturbance beyond what is expected for postpartum, bonding difficulties, intrusive thoughts about harm to infant (ego-dystonic, distinct from psychotic thoughts)
- Screening: Edinburgh Postnatal Depression Scale (EPDS) — score ≥13 indicates likely depression; Item 10 screens for suicidal ideation
- Incidence: 1–2 per 1,000 births; most commonly presents within the first 2 weeks postpartum
- Strong association with bipolar disorder (50% have personal or family history of BD); considered a psychiatric emergency
- Symptoms: sudden onset confusion, disorientation, paranoia/persecutory delusions, hallucinations (auditory/visual), severe agitation, bizarre behaviour, mood lability, insomnia (marked), disorganised speech, risk of infanticide
- Differential: delirium (exclude sepsis — particularly Group A strep endometritis), drug-induced psychosis
Edinburgh Postnatal Depression Scale (EPDS)
The EPDS is a 10-item self-report questionnaire validated for use in the Australian perinatal setting. It is recommended by the RANZCP, COPE (Centre of Perinatal Excellence), and the Australian Government that all women be screened using the EPDS at least twice: at the antenatal booking visit (28 weeks) and at the 6-week postnatal check. Additional screening should occur at any time clinical concern arises.
| EPDS Score | Interpretation | Action |
|---|---|---|
| 0–9 | Depression unlikely | Reassure; re-screen as clinically indicated |
| 10–12 | Possible depression | Clinical interview; monitor closely; offer support services |
| ≥13 | Likely depression | Full clinical assessment; safety planning; refer for treatment (psychotherapy ± pharmacotherapy) |
| Item 10: "self-harm thoughts" — any score >0 | ⚠️ Suicidal ideation | Immediate risk assessment; safety planning; urgent psychiatric referral if active ideation or plan |
Pharmacotherapy in Perinatal Depression
Pharmacotherapy decisions in pregnancy and breastfeeding require careful risk–benefit analysis. Untreated moderate-to-severe depression carries significant risks to both mother and fetus/infant (preterm birth, low birth weight, impaired bonding, adverse child developmental outcomes). In many cases, treatment is safer than non-treatment.
Antidepressants in Pregnancy
Medications to AVOID in Pregnancy and Breastfeeding
| Medication | Pregnancy Risk | Breastfeeding Risk |
|---|---|---|
| Sodium valproate | Category D — CONTRAINDICATED. Neural tube defects (5–10%), neurodevelopmental disorders, reduced IQ. TGA boxed warning. | Excreted in breast milk; generally avoided |
| Lithium | Category D — Ebstein's anomaly (cardiac) risk ~0.05–0.1% (lower than previously thought). Use only if benefits clearly outweigh risks, with close monitoring (serum levels, fetal echocardiography at 18–20 weeks). | Excreted in breast milk; monitor infant lithium levels, thyroid, renal function |
| Paroxetine | Category D — cardiac malformations with first-trimester exposure. Avoid if possible. | Compatible with breastfeeding |
| Carbamazepine | Category D — neural tube defects (1–2%). Avoid if possible. | Low risk in breast milk |
| Benzodiazepines (long-acting) | Category C/D — neonatal sedation, floppy infant syndrome, withdrawal. Use short-acting (e.g., lorazepam) only if essential, for the shortest duration possible. | Sedation in infant; avoid if possible |
| Doxepin | Limited data | CONTRAINDICATED — serious adverse effects reported in breastfed infants |
Treatment of Postnatal Psychosis
- Immediate: Hospital admission (Mother–Baby Unit preferred); ensure safety of mother and infant; 1:1 nursing supervision
- Pharmacotherapy: Atypical antipsychotic (e.g., olanzapine 10–20 mg, quetiapine 300–600 mg) ± benzodiazepine (lorazepam 1–2 mg) for acute agitation; ECT if rapid response needed or catatonic features
- Lithium: Initiate early if bipolar aetiology confirmed (monitor serum levels closely in postpartum period — physiological changes affect pharmacokinetics)
- Long-term: Risk of recurrence after future pregnancies is ~50%; prophylactic mood stabiliser (lithium) from early in subsequent pregnancy
Australian Perinatal Mental Health Resources
Investigations
Before diagnosing a primary mood disorder, exclude organic causes. The following investigations are recommended at baseline for all patients presenting with a new episode of depression or mood disturbance.
Monitoring
Antidepressant Monitoring Schedule
Lithium Monitoring
| Parameter | Frequency | Target / Action |
|---|---|---|
| Serum lithium level | Day 5–7, then weekly × 4, then 3-monthly when stable | Maintenance 0.4–0.8 mmol/L; acute 0.8–1.0 mmol/L |
| eGFR, creatinine, electrolytes | Baseline, then 3-monthly for first 12 months, then 6-monthly | Trend eGFR — progressive decline warrants nephrology referral |
| TSH | Baseline, 6-monthly | Lithium-induced hypothyroidism in ~20% of patients — treat with levothyroxine |
| Calcium, PTH | Baseline, then annually | Lithium-associated hyperparathyroidism |
| Weight, BP | Each visit | Lithium may cause weight gain; counsel re: diet and exercise |
Monitoring Tools for General Practice
- PHQ-9 (Patient Health Questionnaire-9): Validated for severity tracking in Australian primary care; score ≥10 = likely depression; administer at each review
- K-10 (Kessler Psychological Distress Scale): Widely used in Australian GP settings; part of the GP Mental Health Treatment Plan assessment
- GAD-7: For comorbid anxiety assessment
- MDQ (Mood Disorder Questionnaire): Bipolar screening
- DAST-10 / AUDIT: Substance use screening (comorbid substance use worsens mood disorder outcomes)
Special Populations
Pregnancy
Paediatrics & Adolescents
Elderly (≥65 years)
Renal Impairment
Hepatic Impairment
Immunocompromised
Aboriginal and Torres Strait Islander Health Considerations
Aboriginal and Torres Strait Islander peoples experience depression and mood disorders at 2–3 times the rate of the non-Indigenous Australian population. Suicide rates among Aboriginal and Torres Strait Islander peoples are approximately twice the national rate, with devastatingly high rates among young people aged 15–24 (approximately 4 times the non-Indigenous rate). Social and emotional wellbeing (SEW) is conceptualised holistically, encompassing connection to land, culture, spirituality, ancestry, community, and family — not merely the absence of mental illness.
📚 References
- 1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th ed., text rev. Washington, DC: APA; 2022.
- 2. Australian Bureau of Statistics. National Study of Mental Health and Wellbeing, 2020–2022. ABS Cat. No. 4327.0. Canberra: ABS; 2022.
- 3. Australian Institute of Health and Welfare. Mental health services in Australia. AIHW; 2023. Available from: https://www.aihw.gov.au/reports/mental-health-services/mental-health-services-in-australia
- 4. National Health and Medical Research Council. Clinical Practice Guidelines for the Management of Depression in Primary Care. Canberra: NHMRC; 2020 (updated).
- 5. Royal Australian and New Zealand College of Psychiatrists. Australian and New Zealand clinical practice guidelines for the treatment of bipolar disorder. Aust N Z J Psychiatry. 2018;52(11):1035–1070.
- 6. Centre of Perinatal Excellence (COPE). National Perinatal Mental Health Guideline. Melbourne: COPE; 2023. Available from: https://cope.org.au
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- 9. Australian Institute of Health and Welfare. Aboriginal and Torres Strait Islander Health Performance Framework: Mental health. AIHW; 2023.
- 10. Westerman T. Engagement of Indigenous clients in mental health services: What role do cultural differences play? Adv Ment Health. 2004;3(3):88–98.
- 11. Australian Government Department of Health and Aged Care. Medicare Benefits Schedule Book — Category 1: Professional Attendances (GP Mental Health Treatment Plan items 2710, 2712). Canberra: Commonwealth of Australia; 2024.
- 12. Geddes JR, Miklowitz DJ. Treatment of bipolar disorder. Lancet. 2013;381(9878):1672–1682.
- 13. Therapeutic Goods Administration. Valproate and related medicines — new restrictions for use in women and girls of childbearing potential. TGA Safety Alert; 2023. Canberra: Department of Health and Aged Care.
- 14. Beyond Blue. Perinatal depression and anxiety: A guide for GPs. Melbourne: Beyond Blue; 2022. Available from: https://www.beyondblue.org.au
- 15. The Healing Foundation. Working with Aboriginal and Torres Strait Islander people and communities in social and emotional wellbeing. Canberra: The Healing Foundation; 2021.