High levels of preventable chronic disease, injury and mental health problems: mental health problems and illnesses as a priority health issue, including the nature, extent and risk factors

Mental health is a National Health Priority Area and has been since 1996. The HSC syllabus expects you to understand the nature of mental illness, the extent in Australia, the risk factors, and the case for treating it as a priority. This dot point covers all four.

The nature of mental health problems and illnesses

The syllabus uses "mental health problems and mental illness" as overlapping but distinct terms.

Mental health problems are common experiences of distress (sadness, anxiety, stress) that may not meet diagnostic thresholds but affect functioning. Most Australians experience mental health problems at some point.

Mental illness is a clinically diagnosed disorder meeting criteria in the DSM-5 (Diagnostic and Statistical Manual) or ICD-11. The main categories the syllabus expects:

• Mood disorders including major depressive disorder and bipolar disorder.
• Anxiety disorders including generalised anxiety disorder, panic disorder, social anxiety, specific phobias.
• Substance use disorders including alcohol and other drug dependence.
• Psychotic disorders including schizophrenia.
• Eating disorders including anorexia nervosa and bulimia nervosa.
• Personality disorders.
• Neurodevelopmental conditions including ADHD and autism spectrum disorder (the syllabus treats these as overlapping with mental health).

Mental health is best framed as a spectrum, not a binary. The syllabus emphasises that almost all Australians have periods of poorer mental health, and that crossing into clinical illness is a question of severity, duration, and impact on functioning.

The extent of mental health problems in Australia

The headline numbers from the National Study of Mental Health and Wellbeing 2020-22 (ABS):

• Lifetime prevalence. Roughly 1 in 2 Australians aged 16-85 will experience a mental disorder during their lifetime.
• 12-month prevalence. Roughly 1 in 5 Australians experienced a mental disorder in the previous 12 months.
• Young Australians. Prevalence is highest in the 16-24 age group. In 2020-22, 39% of young women and 33% of young men aged 16-24 reported a 12-month mental disorder, up substantially over the last decade.
• Anxiety is the largest single category. Roughly 17% of Australians experienced a 12-month anxiety disorder.
• Mood disorders. Roughly 8% of Australians experienced a 12-month mood disorder (depression, bipolar).

Other relevant Australian data:

• Suicide. Around 3,200 Australians die by suicide each year. Suicide is the leading cause of death for Australians aged 15-44 (ABS Causes of Death). Suicide rates are roughly three times higher in men than in women.
• Hospital admissions. Mental and behavioural disorders account for roughly 1 in 13 hospital admissions (AIHW).
• Treatment gap. Only about half of Australians with a 12-month mental disorder access any treatment, and that proportion has not improved substantially over the last decade despite Better Access and Headspace.

Risk factors for mental illness

Risk factors are conventionally grouped into modifiable and non-modifiable. They interact, and almost never act alone.

Modifiable risk factors

• Substance use (alcohol, cannabis, other drugs). Heavy and early use is associated with higher rates of mood, anxiety and psychotic disorders. Causation runs both ways.
• Sleep. Chronic short sleep is both a symptom and a risk factor for depression and anxiety.
• Physical inactivity. Inactivity is associated with higher depression rates; aerobic exercise has measurable antidepressant effect at moderate intensities.
• Social isolation. A major modifiable risk factor, especially for older Australians and during transitions (school leaving, divorce, retirement).
• Workplace stress including poor job control, high demands, bullying and harassment.
• Financial stress. Strong correlation with mental health problems; not always modifiable at the individual level.
• Childhood adversity and trauma. Modifiable through prevention and early intervention; once experienced, modifiable through trauma-informed treatment.

Non-modifiable risk factors

• Genetics. Strong heritability for bipolar disorder and schizophrenia, moderate for major depression.
• Sex/gender. Women experience higher 12-month rates of mood and anxiety disorders; men have substantially higher suicide rates.
• Age. Highest 12-month prevalence in young adults.
• Childhood trauma. Not modifiable retrospectively, though the consequences can be addressed.

Sociocultural and environmental determinants

• Sociocultural. Family violence, community connection (or lack of), cultural identity loss, stigma around help-seeking.
• Socioeconomic. Low income, unemployment, housing instability, food insecurity all correlate with higher rates of mental illness.
• Environmental. Trauma exposure (natural disasters, violence), urban design (green space access), digital environment (social media use for adolescents).

Why mental health is a priority

Applying the five priority criteria:

• Social justice. Mental illness affects priority groups disproportionately: Indigenous Australians, low-SES Australians, LGBTIQ+ Australians, rural and remote Australians, and young women all show elevated rates or poorer outcomes. Equity violation.
• Priority groups. Affects every named priority group, with widening rather than narrowing gaps for several.
• Prevalence. 1 in 5 Australians in any year, 1 in 2 lifetime. Vastly higher than most other chronic diseases.
• Prevention potential. Real but limited at the population level. Tobacco-style success has not been achieved for mental health.
• Cost. Direct and indirect costs together place mental health among the most expensive single health issues.

This combination is why mental health was added to the National Health Priority Areas in 1996 and remains the most-funded mental health policy area in any developed country (relative to GDP).

The treatment landscape

The syllabus does not require treatment detail here, but a few markers expect you to know.

• Headspace. National youth mental health foundation, 150+ centres, walk-in primary care for 12-25 year olds.
• Better Access (Medicare). Rebated psychology sessions; 10 sessions per year currently (was 20 during COVID).
• Beyond Blue. National information and 24/7 support service.
• Lifeline. 13 11 14, 24/7 crisis support.
• The National Mental Health Workforce Strategy addresses the chronic shortage of psychiatrists and psychologists, particularly in rural and remote Australia.

These programs are evidence of government action under the Ottawa Charter (reorienting health services, building healthy public policy), even where population-level outcomes remain stubborn.