Psychiatry: basic sciences
Psychiatric epidemiology
Psychiatric epidemiology studies how common mental disorders are, who gets them and which factors raise or lower risk. It helps psychiatrists plan services, understand risk factors and read research numbers correctly.
Depth by stage, Pre-U → Consultant (details)
What is it?
Epidemiology counts illness in populations. In psychiatry it answers questions such as how many people have depression, whether schizophrenia is more common in cities, and whether cannabis use raises the risk of psychosis.
It uses measures such as prevalence and incidence and study designs such as cross-sectional surveys, cohort studies and case-control studies. Large national and international surveys give the big picture of mental health burden.
In Malaysia, national health surveys run by the Ministry of Health include mental health measures, and these inform policy. Psychiatrists use such data to plan services and argue for resources.
Why does a psychiatrist need it?
A psychiatrist needs to know which groups are at higher risk, which factors are causes rather than coincidences, and how big a problem is locally. This guides prevention, screening and service planning, and is essential for understanding research and answering exam questions on risk factors for each disorder.
What level is expected at each stage?
Scale: 1. Aware → 2. Understands → 3. Applies → 4. Masters / Teaches. What the levels mean.
- Pre-UNot expected
- Pre-clinicalUnderstandsLearns general epidemiological concepts and study designs.
- ClinicalAwareKnows the approximate frequency of common disorders seen in practice.
- HousemanshipAwareLittle formal application.
- Medical officerAwareAware of local patterns of mental illness and substance use in the community served.
- Psych traineeAppliesKnows prevalence, incidence and key risk factors for each major disorder and critiques study designs.
- Specialist / consultantAppliesUses epidemiological data for service planning, policy input and research.
What are the key topics?
Core measures
- Prevalence (point, period, lifetime) and incidence
- Relative risk, odds ratio and attributable risk
- Disability-adjusted life years (DALYs) and burden of disease
- Standardised mortality ratio and excess mortality in severe mental illness
Study designs
- Cross-sectional surveys
- Case-control studies
- Cohort (longitudinal) studies; birth cohorts
- Ecological studies
- Bias, confounding and Bradford Hill criteria for causation
Key findings
- Global burden of depression and anxiety
- Incidence of schizophrenia and the role of urbanicity, migration and cannabis
- Suicide epidemiology: age, sex, methods
- Epidemiology of dementia in ageing populations
- Treatment gap: the proportion of people with disorders who receive no care
Malaysian and regional context
- Mental health findings from the National Health and Morbidity Survey (Ministry of Health)
- Substance use patterns in Malaysia (e.g. opioids, amphetamine-type stimulants, kratom)
- Urban–rural and ethnic differences in help-seeking
- Changes in suicide reporting after the 2023 decriminalisation of attempted suicide (an area to watch)
How is it learned and assessed?
- Epidemiology and biostatistics teaching in pre-clinical and community medicine years
- Basic sciences in psychiatry training; examined in MMed Psychiatry Part I and MRCPsych Paper A (and critical review in Paper B)
- Applied in the dissertation and in journal clubs
Typical textbooks and resources
- Textbook in Psychiatric Epidemiology — Tsuang, Tohen and Jones
- Oxford Textbook of Psychiatry — epidemiology sections for each disorder
- National Health and Morbidity Survey reports — Ministry of Health Malaysia
- WHO mental health reports and Mental Health Atlas
Titles are widely used examples; editions change. Use university libraries or legitimate purchases.
Common questions
How common is mental illness in Malaysia?
Ministry of Health national surveys show that mental health problems affect a meaningful share of Malaysian adults and children, with depression and anxiety the most common. Figures differ by survey year and method, so it is best to read the latest National Health and Morbidity Survey report directly.
What is the difference between prevalence and incidence?
Prevalence is how many people have a condition at a given time; incidence is how many new cases appear over a period. A long-lasting illness can have high prevalence even if incidence is low.