How do we define and explain mental health and disorder?
Compare models used to define and explain mental health and mental disorder, including the biopsychosocial model and approaches to classifying normality
Mental health and disorder can be understood through biological, psychological and social lenses. The biopsychosocial model integrates all three, while defining normality itself is contested.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
You need to explain how mental health and disorder are defined, compare the models used to explain them, and recognise the difficulty of deciding what is normal.
Defining mental health and disorder
Mental health is a state of wellbeing in which a person realises their abilities, copes with the normal stresses of life, works productively and contributes to their community. It is not simply the absence of illness, but lies on a continuum.
A mental disorder generally involves patterns of thoughts, feelings or behaviours that are distressing, dysfunctional, deviant from social norms, or dangerous (the "four Ds"), and that significantly impair daily functioning.
Approaches to defining normality
Deciding what counts as normal or abnormal is contested. Common criteria include:
- Statistical - behaviour that is rare or far from the average is abnormal. Limitation: rare can be desirable (high intelligence) and common can be unhealthy.
- Social norms - behaviour that violates cultural expectations is abnormal. Limitation: norms vary across cultures and change over time.
- Functional - behaviour that prevents a person coping with daily life is abnormal (maladaptive).
- Distress - behaviour causing significant personal suffering. Limitation: some disorders involve little subjective distress.
Because no single criterion is sufficient, clinicians use a combination.
Models explaining mental disorder
- Biological (medical) model
- Disorders arise from physical causes such as genetics, brain structure, and neurotransmitter imbalances (for example, low serotonin linked to depression). Treatment focuses on medication and physical therapies. Strength: scientific and supports effective drug treatments. Weakness: can ignore life experiences and social context.
- Psychological models
- These emphasise mental processes: psychodynamic (unconscious conflict), behavioural (disorders as learned responses), and cognitive (faulty or unhelpful thinking patterns). Strength: explains the role of experience and thought. Weakness: may underplay biology.
- Social model
- Disorders are shaped by social factors such as poverty, discrimination, relationships, culture and stressful life events. Strength: highlights environment and inequality. Weakness: does not explain individual differences in who develops a disorder.
The biopsychosocial model
The biopsychosocial model integrates all three: biological vulnerability, psychological processes and social circumstances interact to influence mental health. A related idea is the diathesis-stress model, in which a person with an underlying predisposition (diathesis) develops a disorder only when sufficient stress occurs.
This integrated view also shapes how disorders are classified and diagnosed. Clinicians in Australia use the DSM-5 (the Diagnostic and Statistical Manual of Mental Disorders) or the ICD-11 to apply consistent criteria. Standardised classification improves reliability (different clinicians reach the same diagnosis) and communication, but it has been criticised for medicalising normal experiences, for labelling effects (a diagnosis can become a self-fulfilling expectation), and for cultural bias when criteria developed in one society are applied to another. SACE answers gain marks for noting that diagnosis is useful but not value-free.
Exam-style practice questions
Practice questions written in the style of SACE Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SACE 20226 marksJordan has a family history of depression. After moving interstate for work and becoming socially isolated, Jordan develops a depressive disorder. (a) Use the biopsychosocial model to identify one biological, one psychological and one social factor that may have contributed to Jordan's disorder. (b) Explain how the diathesis-stress model accounts for why the disorder emerged at this point in time.Show worked answer →
This is a research/application item marked on knowledge and application. Work part by part.
(a) Three factors (3 marks, 1 each). Biological: the family history of depression suggests a genetic vulnerability, perhaps linked to serotonin functioning. Psychological: a tendency toward negative thinking or low self-esteem would be a psychological factor (any plausible cognitive or personality factor earns the mark). Social: the recent interstate move and social isolation are clear social stressors. Each factor must be correctly labelled by level.
(b) Diathesis-stress (3 marks). The diathesis-stress model says a disorder appears only when an underlying predisposition (diathesis) meets a sufficient stressor. Jordan carried a biological vulnerability for some time without becoming unwell. The disorder emerged when the stress of relocating and losing social support crossed the threshold needed to trigger it in someone already predisposed. This explains the timing: vulnerability alone or mild stress alone would not have produced the disorder, but their combination did.
SACE 20218 marksCompare the biological (medical) model and the social model as explanations of mental disorder. In your answer, evaluate the strengths and limitations of each and explain why the biopsychosocial model is often preferred.Show worked answer →
This is an extended-response item marked on knowledge and evaluation. Use a compare-evaluate-resolve structure.
- Biological model
- Explains disorder through physical causes: genetics, brain structure and neurotransmitter imbalances (for example low serotonin in depression). Strength: it is scientific, testable and underpins effective drug treatments. Limitation: it can reduce a person to their biology and ignore life experience and social context, and drugs treat symptoms rather than causes.
- Social model
- Explains disorder through social factors such as poverty, discrimination, relationships and stressful life events. Strength: it highlights the role of environment and inequality and points to prevention through social change. Limitation: it cannot explain why, within the same environment, only some individuals develop a disorder.
- Why biopsychosocial is preferred
- Each model alone is partial: the biological model explains individual vulnerability but not context, the social model explains context but not individual differences. The biopsychosocial model integrates biological vulnerability, psychological processes and social circumstances, and the diathesis-stress idea shows how they interact. A top answer concludes that the integrated model fits the evidence better because most disorders are multiply determined.