PSYC1024 · Anxiety, Mood and Stress
Mood and Depression
Week 8 covers mood disorders with a focus on depression: the core symptoms and diagnostic features of major depressive disorder, how it differs from ordinary low mood, and current models of its neurobiology and psychology — relating mood back to the emotion/affect framework of Week 2 (mood = long-lasting, diffuse, low aboutness). It is final-exam examinable (the 40% Inspera final covers all topics). (Week 8's own lecture slides were not among the materials this guide was built from, so the criteria and models below are discipline-standard first-year canon — confirm against your Moodle notes. If any of this material feels personally relevant, a GP is the recommended first step and emergency support is available on 000.)
What this chapter covers
- 01Mood disorders vs anxiety: disturbance of emotional state/valence rather than threat/apprehension
- 02Major Depressive Disorder (MDD): ≥5 of 9 symptoms over the same 2-week period, including ≥1 core symptom
- 03The two core symptoms: depressed mood and anhedonia (loss of interest/pleasure)
- 04Persistent Depressive Disorder (dysthymia): depressed mood most days for ≥2 years
- 05Bipolar disorders: Bipolar I (≥1 manic episode) vs Bipolar II (hypomania + major depression)
- 06The monoamine hypothesis: reduced serotonin, noradrenaline and dopamine activity (now seen as incomplete)
- 07Beck's cognitive model: the negative cognitive triad, negative schemas and cognitive distortions
- 08The behavioural model and learned helplessness/hopelessness; diathesis–stress integration
Does this meet the MDD criteria — and is it unipolar?
- +1State the rule: MDD requires at least 5 of 9 symptoms during the same 2-week period, and at least one must be a core symptom — either (1) depressed mood or (2) anhedonia (loss of interest/pleasure). Both core symptoms are present here.
- +1Count the symptoms against the rule: depressed mood, anhedonia, insomnia, fatigue, poor concentration, worthlessness and appetite loss = 7 of 9, sustained for three weeks (beyond the 2-week minimum) and representing a change from prior functioning. So the symptom-count and duration criteria are met (assuming clinically significant distress/impairment and no substance/medical cause).
- +1(b) Distinguish it from ordinary low mood: everyday sadness is usually shorter, proportionate to an identifiable trigger, and does not cluster five or more symptoms with impairment across a two-week span. The 2-week duration, the symptom count and the functional impairment are what lift it over the threshold.
- +1(c) What points to bipolar: a history of a manic episode (≥1 week of abnormally elevated or irritable mood plus increased energy, with features like decreased need for sleep, grandiosity, pressured speech or risky behaviour) indicates Bipolar I; a hypomanic episode plus major depression indicates Bipolar II. Depressive episodes with no history of mania/hypomania point to unipolar MDD.
Key terms
- Major Depressive Disorder (MDD)
- At least 5 of 9 symptoms during the same 2-week period, representing a change from prior functioning, including at least one core symptom — depressed mood or anhedonia. Must cause distress/impairment and not be due to a substance or medical condition.
- Anhedonia
- A markedly reduced interest or pleasure in activities once enjoyed — one of the two core symptoms of MDD (the other being depressed mood). At least one core symptom must be present for the diagnosis.
- Persistent Depressive Disorder (dysthymia)
- Depressed mood most of the day, more days than not, for at least 2 years (1 year in youth), with additional symptoms. Chronic but often less severe than a full MDD episode.
- Bipolar I vs Bipolar II
- Bipolar I requires at least one manic episode (≥1 week of abnormally elevated/irritable mood plus increased energy and associated symptoms); Bipolar II requires at least one hypomanic episode plus at least one major depressive episode, with no full mania.
- Monoamine hypothesis
- The proposal that depression is linked to reduced activity of the monoamine neurotransmitters serotonin, noradrenaline and dopamine. It underpins how antidepressants act but is now regarded as an incomplete account.
- Beck's cognitive model
- Depression is maintained by the negative cognitive triad (negative views of the self, the world and the future), negative schemas and cognitive distortions. The basis of cognitive restructuring in CBT (Week 9).
Mood and Depression FAQ
What are the criteria for major depressive disorder?
At least 5 of 9 symptoms present during the same 2-week period, representing a change from prior functioning, and including at least one of the two core symptoms — depressed mood or anhedonia (loss of interest or pleasure). The other symptoms include appetite/weight change, sleep disturbance, psychomotor changes, fatigue, worthlessness or guilt, poor concentration, and recurrent thoughts of death. The episode must cause distress or impairment and not be explained by a substance or medical condition.
How is depression different from ordinary sadness?
Ordinary sadness is usually shorter, proportionate to an identifiable trigger, and does not knock out your functioning. Major depression is defined by a cluster — at least five symptoms including a core symptom, sustained for at least two weeks, causing distress or impairment. Mood, in the Week 2 sense, is long-lasting and diffuse, and a depressive episode is that low state crossing a clinical threshold of duration, symptom count and impairment.
What is the difference between unipolar and bipolar depression?
Unipolar depression (MDD) involves depressive episodes only. Bipolar disorders involve elevated-mood episodes too: Bipolar I requires at least one manic episode (a week or more of abnormally elevated or irritable mood with increased energy and features like reduced need for sleep or grandiosity), while Bipolar II involves hypomania plus major depression. That is why clinicians screen for any history of mania or hypomania before treating depression as unipolar.
Can AI help me with the mood-disorders material?
Yes. Sia can drill you on the MDD criteria (the 5-of-9, 2-week, core-symptom rule), help you distinguish unipolar from bipolar, and walk through the monoamine, cognitive and behavioural models step by step. It mirrors how the content is assessed at UNSW; it does not sit the final for you, and UNSW academic-integrity rules apply.
Exam move
Depression questions reward exact criteria, so commit the MDD rule to memory as three moving parts — at least 5 of 9 symptoms, over at least 2 weeks, including at least one core symptom (depressed mood or anhedonia) — and practise counting symptoms in vignettes. Always screen for a manic or hypomanic history before labelling a case unipolar, and be able to place Bipolar I vs Bipolar II on that distinction. Keep the aetiological models distinct and one-line ready: the monoamine hypothesis (reduced serotonin/noradrenaline/dopamine, now seen as incomplete), Beck's negative cognitive triad, learned helplessness/hopelessness, and the behavioural loss-of-reinforcement model — because the final often tests the mechanism behind a treatment you meet in Week 9. Tie mood back to the Week 2 emotion/affect framework (mood = long, diffuse, low aboutness) so the concepts reinforce each other. Because Week 8's own lecture materials were not among the materials this guide was built from, confirm the criteria wording on Moodle. Ask Sia for extra vignettes and to check your symptom counts.
Working through Mood and Depression in PSYC1024? Sia is AskSia’s AI Psychology tutor — ask any PSYC1024 Mood and Depression question and get a clear, step-by-step explanation grounded in how PSYC1024 is taught and assessed. Read this chapter free, then take your hardest questions to Sia.
