Singapore Statistics on Mental Health 新加坡心理卫生数据

Dear readers, 

I am no statistician (prevalence anyone?), but the rates of mental illness in Singapore should be in the ballpark of Malaysia's  (Today 23 July 2013: 1 in 5 Malaysians has a mental health problem, says Deputy Health Minister even higher, due to higher urbanisation and stressful living

 I would take ST's report that '1 in 10 will suffer from mental illness' ( with a truckload of salt.

P.S. In fact, the ST uses lifetime prevalence for the "1 in 10" figure which should be even higher than point prevalence or one-year prevalence in the Malaysian "1 in 5" statistics, at least to this novice statistician. 

'1 in 10 will suffer from mental illness'

Common disorders include depression and alcohol abuse: Study

By Chang Ai-Lien, The Straits Times, 19 Nov 2011

MORE than one in 10 people in Singapore will be stricken by mental illness in their lifetime, according to a large, new study here.


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Mental disorders have an immense impact on individuals and their families pose a growing challenge to the healthcare systems throughout the world. The aging population and the trend of social changes (such as increasing divorce rates, changing family structures, and economic pressures) pose great challenges to the mental well-being of Singapore.

IMH has embarked on a nationwide program: The Singapore Mental Health Study (SMHS). The SMHS brings together international and local expertise for an extensive and comprehensive assessment of the nation's mental health.

This project aims to:

Conduct a population-based study to establish the positive and negative mental health status of the Singaporean population.

Assess the spectrum and distribution of different types of mental illnesses across the three major ethnic groups.

Develop and validate a tool for the assessment of positive mental wellbeing for the Singapore population.

Describe the current use of mental health services (both Western and traditional medicines) and the level of unmet needs and identify facilitators and barriers to mental health care and the financial, social and personal costs associated with mental illness.

This project involves collaborations between multiple stakeholders and experts from leading national and international institutions.

This three-year S$6.9-million programme is funded by the Singapore Millennium Foundation and the Ministry of Health (MOH), Singapore.

Principal Investigator:

A/Prof Chong Siow Ann, Institute of Mental Health

Co-Principal Investigators:

A/Prof Mabel Yap, Ministry of Health

Dr Lim Yee Wei, RAND Health

A/Prof Kwok Kian Woon, Nanyang Technological University


Information updated as at 10 October 2013.
Please seek further clarifications with IMH Corporate Communications Department when
using the following data.
Media Release

18 November 2011

Latest study sheds light on the
state of mental health in Singapore

1. The Singapore Mental Health Study (SMHS) conducted in 2010 and spearheaded
by the Institute of Mental Health (IMH), has been completed. This nationwide
epidemiological study gives insight into some of the common mental illnesses in the adult
Singapore resident population, the associated factors of these illnesses, the delay in
seeking treatment, and the period of delay among those who eventually sought

2. Key findings from the study show that:

• Among the illnesses assessed in this study, Major Depressive Disorder (MDD),
Alcohol Abuse and Obsessive Compulsive Disorder (OCD) emerged as the top
three most common disorders in Singapore. One in 17 people in Singapore
have suffered from MDD at some time in their lifetime, while Alcohol Abuse and
OCD affected one in 32 and one in 33 people, respectively.

• Socio-demographic characteristics such as age, gender, ethnicity, education
and employment status were associated with the prevalence of mental illness.

• The majority of the mental illnesses occurred by the age of 29 years.

• The majority of the people with mental illness were not seeking help.
 Affective Disorders

3. According to the study, MDD was the most common mental illness in Singapore.
5.8% of the adult population in Singapore suffered from MDD at some time in their
lifetime. In the previous 12 months (prior to the survey), 2.2% of the adult population had

4. The illness affected over 57,000 adult men and about 102,000 adult women during
their lifetime. Depression was also associated with chronic physical illnesses. About half
(49.2%) of people with MDD had at least one chronic physical illness.

5. 1.2% of the adult population in Singapore suffered from Bipolar Disorder. It affected
men and women equally.

Anxiety Disorders
6. Both Generalised Anxiety Disorder (GAD) and OCD are anxiety disorders. About
100,000 individuals in our local population suffered from anxiety disorders during their
lifetime. Overall, 3.6% suffered GAD and OCD during their lifetime. Nearly half of those
with GAD (40.2%) also had a chronic physical illness.

7. OCD was more common than GAD (3.0% and 0.9% respectively). In the previous 12
months (prior to the survey), 1.1% and 0.4% of the adult population had OCD and GAD

Alcohol Use Disorders

8. About 3.1% and 0.5% of the population suffered from Alcohol Abuse and Alcohol
Dependence respectively at some time in their life. Over the previous 12 months, the
prevalence of Alcohol Abuse and Alcohol Dependence was 0.5% and 0.3%,
respectively. More men were found to abuse alcohol than women (ratio of 4:1). Overall,
the prevalence rate is low compared to other countries like US, Europe, China, Australia
and New Zealand.

9. There was a large gap in help-seeking behaviour among those with alcohol abuse,
with 96.2% of those affected not seeking help.

Nicotine Dependence
9. At the point of the survey, 4.5% of the population were found to suffer from Nicotine Dependence. Men and those with lower education were more likely to have Nicotine

Age of Onset of Illness, Time to Seeking Help and Treatment Gap
10. Most people who suffered from a mental illness had their first onset of illness when
they were in their twenties.

11. The study found that a large gap in help-seeking behaviour (also known in the
scientific literature as the “treatment gap”) exists for the majority of mental illnesses. This
means that people with mental illness were not seeking professional help.

12. The average time (median) taken to seek help from the start of illness was for those
with Alcohol Abuse (14 years); followed by Bipolar Disorder and OCD (9 years), GAD (6
years) and MDD (5 years).

13. Among all the people with a mental illness in their lifetime, 22.1% had consulted a
psychiatrist. The majority had seen a professional care-giver in the community – 21.6%
went to a counselor, 18% went to a GP, and 12.0% went to a religious or spiritual healer.

14. There was an association between mental illness and chronic physical illness.
14.3% of those with a chronic physical illness also had a mental illness. Among those
with mental illness, 50.6% had a chronic physical illness.

15. “This survey has provided a rich body of information on the prevalence of mental
illnesses and problems. We hope it will serve as useful data to inform the development
and refinement of policies and mental health services, ‘’ said A/Prof Chong Siow Ann, the
principal investigator of the study, and Vice-Chairman, Medical Board (Research), IMH.

- END -
 For media queries, please contact:
Ms Penny Chua
Senior Manager, Corporate Communications
Institute of Mental Health
DID: 6389 2865 HP: 8133 1821

About the Institute of Mental Health
The Institute of Mental Health is the only tertiary mental health centre in Singapore. It
offers a multi-faceted and comprehensive range of psychiatric, rehabilitative and
counseling services to meet the needs of three groups of patients – children and
adolescents, adults and the elderly. IMH also runs mental health education
programmes for the general public. These programmes aim to promote mental wellness
and raise awareness of the importance and benefits of prevention, early detection and
treatment of mental disorders. Annex 1

The study was undertaken by a multi‐disciplinary team led by the Institute of Mental
Health and is a collaborative effort between four centres – IMH, Ministry of Health (MOH),
Nanyang Technological University (NTU) and RAND Health, a research division within
RAND Corporation, an American non-profit research organisation. The $6.9 million study
was funded by the Singapore Millennium Foundation (SMF) and MOH.

The Principal Investigator of this study is A/Prof Chong Siow Ann, Vice Chairman Medical
Board (Research) IMH, and Senior Clinician-Scientist Investigator, National Medical
Research Council. Other than A/Prof Chong, the team is also led by Dr Mythily
Subramaniam and Ms Janhavi Vaingankar, from the Research Division in IMH.

A total of 6,616 Singapore Residents (including Singapore Citizens and Permanent
Residents) aged 18 years and above living in households Singapore were interviewed in
depth for the study during the field research phase in 2010. The first household was
contacted on 2nd Dec 2009 and the last interview was completed on 5th Dec 2010. The
response rate was 75.9%.

 Annex 2


Major Depressive Disorder

Major depressive disorder (MDD) is characterised by a depressed mood: a profound
feeling of sadness, emptiness, worthlessness and hopelessness. Associated with this, is
a range of other disturbances like loss of interest in activities and loss of pleasure in
almost all activities, sleep disturbances (either not being able to sleep well or sleeping to
much), loss of appetite with consequent loss of weight although in atypical cases, there
might be overeating. Significant impairment in functioning is brought on by difficulty
concentrating, loss of energy, tiredness and listlessness. The depressed person may
have suicidal thoughts or intentions which might lead to suicidal attempts or even actual

Bipolar Disorder

This disorder is characterized by mania which is an abnormally elevated, expansive, or
irritable mood. Together with this, there may be an inflated sense of self-esteem or even
grandiosity, decreased need for sleep, and talkativeness, agitation and a tendency to
engage in activities which while pleasurable, would have painful consequences like
spending sprees, without the money to pay for them, increased sexual activity, reckless
driving, rash business and personal decisions. This state is often severe enough to
seriously affect the person’s life and often hospitalization is required to protect the
individual from the damaging consequences of the lack of restrain and judgment. A
subtype of bipolar disorder is the occurrence of mania with a major depressive episode.

Generalised Anxiety Disorder

The essential feature of generalised anxiety disorder (GAD) is a general feeling of
excessive anxiety and worry that is difficult to control. These feelings are not related to
any specific event or object but may be about a number of events and activities. They are
often accompanied by other symptoms like restlessness, fatigue, irritability, and or
disturbed sleep. GAD can be chronic and recurrent in nature, impair family life, and
reduces social adjustment and functioning. Typically GAD develops over a period of time
and may not be noticed until it is significant enough to cause problems with functioning.

 Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is characterized by the occurrence of either
obsessions, compulsive rituals or, most commonly, both recurrent and persistent thoughts,
impulses, or images that are experienced as intrusive and cause great anxiety. They are
not simply excessive worries about real life issues; the affected individual attempts to
ignore, suppress, or neutralise them with some other thought or action and recognizes
that these thoughts are a product of his or her mind. Examples of obsessions include
unwanted thoughts or images of harming loved ones, persistent doubts that one has not
locked doors or switched off electrical appliances, and intrusive thoughts of being
contaminated. Compulsions are repetitive behaviours (eg, repetitive hand washing or
checking) or mental acts (eg, repetitive praying, counting, or thinking good thoughts to
undo or replace bad thoughts) that the affected individual feels compelled to do in
response to an obsession, or according to rigid rules (eg, checking that a light switch is
turned off by switching it on and off exactly ten times).

Alcohol Abuse

Alcohol abuse is diagnosed when one or more of the following occurs:
a) Recurrent alcohol use resulting in failure to fulfill major role obligations at work,
school, or home (e.g., repeated absences or poor work performance related to
alcohol use; alcohol-related absences, suspensions or expulsions from school;
or neglect of children or household)
b) Recurrent use in situations in which it is physically hazardous (e.g., driving a
car while under the influence of alcohol)
c) Having alcohol-related legal problems (e.g., arrests for alcohol-related
disorderly conduct).
d) Continuing to use alcohol despite having persistent or recurrent social or
interpersonal problems caused or worsened by the effects of alcohol (e.g.
arguments with wife over consequences of being drunk, fights)

Alcohol Dependence

Alcohol dependence is defined as a maladaptive pattern of alcohol use, leading to
clinically significant impairment or distress, and the essential feature of which is a cluster
of cognitive, behavioral and physical symptoms. These include tolerance (a need for
markedly increased amounts of alcohol to achieve intoxication or desired effect),
unpleasant withdrawal symptoms when intake is stopped or reduced, a consuming
preoccupation to obtain and use alcohol at the expense of other important social, occupational and recreational activities. Despite this, the person would persist in using
alcohol and even with the knowledge of having a recurrent physical or psychological
problem that is likely to have been caused or exacerbated by the alcohol (e.g., continued
drinking despite recognition that an ulcer was made worse by alcohol consumption).


Life-time Prevalence

Prevalence of any disorder is the proportion of people affected with that disorder in a
given population at a specific time. Life-time prevalence is the number of people in a
population that have had the disorder at any time in their life, divided by the total number
of individuals in the population at the time of assessment. It estimates the extent of a
disorder within a population over a certain period of time.

12- month Prevalence

Annual or 12-month prevalence is the number of people in a population that have had a
disorder during a specific year divided by the total number of individuals in the population.
It includes cases arising before but extending into that year and new cases identified in
that year. It is often used to estimate impact of a disorder within a population in that year.

Treatment Gap

Treatment gap is the proportion of people having a disorder yet not receiving treatment
for it. In this study, under each diagnostic section, respondents are asked whether they
had ever in their life talked to a medical doctor or other professional about the disorder
under investigation. Example of the question from Depression module: “Did you ever in
your life talk to a medical doctor or other professional about your
(sadness/or/discouragement/or/ lack of interest)? (By professional we mean
psychologists, counselors, spiritual advisors, herbalists, acupuncturists, and other healing

Sampling and Weight adjustment

Disproportionate sampling was used to randomly select residents for the survey
(i.e. the percentage of residents belong to different age groups and ethnicities
were not similar to their distribution in the Singapore population), and therefore
people belonging to Malay and Indian ethnicity and those above 65 years of age
were over sampled. This method was applied to identify an adequate number of people in these sub-groups with a mental disorder to allow statistically sound
comparisons between sub-groups. Because of the complex sampling design of
the survey, it is important to make use of sampling weights for weight adjustment
to eventually produce representative estimates for the Singapore resident
population. For example, if you apply weight adjustment to prevalence rates for
respondents who are 30 % Chinese, 30% Malay and 30% Indian you will be able
to get rates for a population with 70% Chinese, 12 % Malay and 8% Indian.

Odds Ratio

The odds ratio (OR) is a statistical term used to assess the risk of a particular
outcome (or disorder) in presence of a certain factor. It is a relative measure of
risk that tells how much more likely it is that someone who is exposed to the factor
will develop the outcome (or disorder) as compared to someone who is not
exposed. For example, when investigating differences in prevalence of
depression across men and women, gender is treated as exposure and
depression is the outcome. Upon statistical analysis, if the OR is 1.8, it can be
interpreted as women had 1.8 times higher odds of having depression as
compared to men.


P-value is a statistical term that gives the probability of a chance occurrence, with
a value ranging from zero to one. P-values can be derived using various methods
and are used for detecting statistical differences between two populations. For
example, if the P value is 0.04, it means that there is a 4% chance of observing a
difference as large as observed between the two populations even if there were in
reality no differences. Values less than or equal to 0.05 are often used as a cut off
to infer a statistical difference between two groups.
 Annex 3

About the Singapore Millennium Foundation and Temasek Trust
Established in February 2002, the Singapore Millennium Foundation (SMF) is a
Singapore Institution of a Public Character and a non-profit philanthropic organisation set
up jointly by the then Singapore Technologies and Temasek Holdings. The SMF aims to
promote research in Singapore and raise Singapore’s international visibility as a centre of
knowledge creation -- a place where progressive researchers meet to exchange ideas,
challenge findings and jointly advance the knowledge capital of the world.

Temasek Trust was established in 2007 to independently oversee the financial
management of Temasek’s philanthropic endowments and gifts, including the endowment
disbursements to approved non-profit beneficiaries.
 Annex 4
Researchers’ Profile

Chong Siow Ann

Associate Professsor Siow-Ann Chong is the Vice Chairman of Medical Board
(Research), Senior Consultant Psychiatrist and Chairman of the Clinical Research
Committee at the Institute of Mental Health, as well as a member of the National
Medical Research Council of Singapore. He was a Senior Consultant to the
Health Service Research and Evaluation Division of the Ministry of Health of
Singapore, and a member of the Director of Medical Services Taskforce on the
National Mental Health Blueprint and Policy among other committees.

His research interests are psychosis, psychiatric genetics, epidemiology, and
health service research. He has published widely and is the Associate Editor of a
few journals and sits in the Editorial Board of several journals.

He has won several research awards – including the Inaugural 2006 World Health
Organisation and State of Kuwait Prize for Research in Mental Health Promotion,
the Clinical Scientist Investigator Award (Category A) from the Biomedical
Research Council and National Research Council of Singapore in 2007, the
Inaugural 2008 National Medical Excellence Award (team) from the Ministry of
Health (Singapore), the National Healthcare Group Distinguished Award (2008),
the Galloway Memorial Lecture and Gold Medal (2011) awarded by the Singapore
Academy of Medicine.

He is the Principal Investigator of the Singapore Mental Health Study and the
Flagship Translational and Clinical Research Programme in Neuroscience which
is a 5-year multinational study which sets out to determine the biomarkers of
schizophrenia and related psychoses. Mythily Subramaniam

Dr Mythily Subramaniam is the Deputy Director of Research at the Institute of
Mental Health. She has over ten years of experience in mental health research.

Her research interests are in the areas of psychosis, addictions, epidemiology,
and health service research. She has worked on several research projects with
the Ministry of Health, Singapore Prison Authority, Ministry of Defence, Ministry of
Community Youth and Sports Development, and the Agency for Integrated Care.
She has published extensively and is a reviewer for several scientific journals.

She is a co-investigator of the Singapore Mental Health Study and the 5-year,
25-million-dollar Flagship Translational Clinical Research Programme in
Neuroscience. She will be leading a national-wide study of the elderly population
in Singapore to establish the prevalence of dementia and the burden of care.

Janhavi Vaingankar
MSc (Epidemiology)

Ms Janhavi Vaingankar is a Manager and Researcher at the Research Division of
the Institute of Mental Health. Trained as an epidemiologist from the London
School of Hygiene and Tropical Medicine, University of London, she has over ten
years of experience in facilitating and conducting research studies and has been
a co-Investigator for several research projects, including projects undertaken for
the Ministry of Health, Ministry of Community Development, Youth and Sports,
Singapore, and the Agency for Integrated Care.

She is a recipient of the National Medical Research Council (Singapore) Medical
Research Scientist Award. Her areas of research are psychiatric epidemiology,
mental well being and health services research and she has published in these

She is a Co-Investigator of the Singapore Mental Health Study and has taken the
lead in developing and validating a culturally valid instrument to measure positive
mental health in the Singapore population.


The results of the Singapore Mental Health Study can be found at::

 2012 Feb;41(2):49-66.

A population-based survey of mental disorders in Singapore.


Research Division, Institute of Mental Health, Singapore.



Mental illnesses are not only a growing public health concern but also a major social and economic issue affecting individuals and families throughout the world. The prevalence of mental disorders, the extent of disability caused by these disorders, and services utilisation of these patients has been well studied in developed countries. The aim of this study was to establish the prevalence of select mental disorders and their associated sociodemographic correlates in the adult Singapore resident population.


This was a cross-sectional, populationbased, epidemiological study of adult Singapore residents aged 18 years and above. The subjects were randomly selected using a disproportionate stratified sampling method. The diagnoses of selected mental disorders including major depressive disorder (MDD), dysthymia, bipolar (bipolar I & II) disorders, generalised anxiety disorder (GAD), obsessive compulsive disorder (OCD), alcohol abuse and alcohol dependence were established using the Composite International Diagnostic Interview, which is a fully structured diagnostic instrument that assesses lifetime and 12-month prevalence of mental disorders.


Among the 6616 respondents (response rate of 75.9%), 12.0% had at least one lifetime affective, anxiety, or alcohol use disorders. The lifetime prevalence of MDD was 5.8% and that of bipolar disorder was 1.2%. The combined lifetime prevalence of the 2 anxiety disorders, GAD and OCD was 3.6%, with the latter being more common than GAD (0.9% and 3.0% respectively). The lifetime prevalence of alcohol abuse and dependence were found to be 3.1% and 0.5% respectively. Age, gender, ethnicity, marital status and chronic physical illnesses were all significant correlates of mental disorders.


The identified associated factors would help guide resource allocation, policy formulation and programme development in Singapore.
[PubMed - indexed for MEDLINE] 
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Subsequent analysis based on the same survey:

 2012 Mar;41(3):105-14.

Prevalence and impact of mental and physical comorbidity in the adult Singapore population.


Research Division, Institute of Mental Health, Singapore.



This study aims to assess the prevalence rates of mental disorders and chronic medical conditions in the Singapore resident population, and examine their association and respective impact on the quality of life.


A household survey was carried out on a nationally representative sample of the adult (18 years and above) resident population. The main instrument used to establish the diagnosis of mental disorders is the World Mental Health Composite International Diagnostic Interview (WMH-CIDI). The mental disorders included in study were major depressive disorder, bipolar disorder, generalised anxiety disorder, obsessive compulsive disorder, alcohol abuse and alcohol dependence. Respondents were asked if they had any of the chronic medical conditions from a list of 15 conditions. Health-related quality of life was assessed with the EQ-5D.


Of the 6616 respondents, the lifetime prevalence of mental disorders was 12.0%, and that of chronic medical disorders were 42.6% and those with comorbid mental and medical disorders was 6.1%. The prevalence of any physical disorder in this population was high (42.6%). Among those with chronic physical disorders, 14.3% also had a mental disorder, and among those with mental disorders, more than half (50.6%) had a medical disorder. Most of the mental disorders were not treated. Males, Indians, older people, and those who were separated or divorced were more likely to have comorbidity. The health-related quality of life was significant worse in those with both mental and medical disorders compared to those with either mental or medical disorder.


Our study re-emphasised the common occurrence of mental and medical disorders and the importance for an integrated care system with the capability to screen and treat both types of disorders. It also identified certain subpopulations which are more likely to have comorbidity for which a more targeted intervention could be planned.
[PubMed - indexed for MEDLINE] 
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 2012 Apr;41(4):154-60.

Where do people with mental disorders in Singapore go to for help?


Research Division, Institute of Mental Health, Singapore.



This study aims to examine the pattern of services utilisation and the factors associated with help-seeking behaviour among those with mental disorders in the multi-ethnic Asian population of Singapore.


A household survey was carried out on a nationally representative sample of the adult (18 years and above) resident population. The main instrument used to establish the diagnosis of mental disorders and the services sought was the Composite International Diagnostic Interview version 3.0 (CIDI 3.0). The 'services' component of the instrument contains questions, which examine service utilisation for mental health problems.


A total number of 6616 completed respondents constituted a representative sample of the adult resident population in Singapore. Only 31.7% of those with mental disorders had sought help: 15.7% from mental health providers, 8.4% from general practitioners, and 7.6% from religious/ spiritual advisors or other healers. Among respondents with severe disability across any disorder assessed in our survey, 50.1% had sought help from some service in the past 12 months. Individuals with moderate or mild levels had lower rates of consultation, i.e. 35.4% and 30.6% respectively. The rate of using the Internet as a source of help was low in this population.


There is a need to engage and work collaboratively with healthcare providers (including religious and spiritual healers) in the community to detect, assess and treat those with mental illness. More general practitioners need to be involved, and the role of the Internet also requires further consideration as a source for help.
[PubMed - indexed for MEDLINE] 
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 2012 May;41(5):212-20.

"How much can I take?": predictors of perceived burden for relatives of people with chronic illness.


Research Division, Institute of Mental Health, Singapore.



Chronic illnesses are common and have detrimental effects not only on the affected individuals but also on their families. These negative consequences on the physical and psychological health of caregivers constitute the burden of care. We investigate the predictors of perceived burden of care among relatives of people with any chronic physical or mental illness using secondary data from a nationwide survey in Singapore.


A cross-sectional household survey was conducted among adult residents of age 18 years and above and data were analysed to explore the predictors of high perceived burden of care. Two thousand four hundred and fifty-eight respondents having at least 1 close relative with any chronic physical and/or mental illness were included.


Majority of the respondents had at least 1 close family member with physical illness (88.3%)--the most common illnesses reported were memory problems (86.9%), physical disability (74.8%), heart problems (70.1%) and cancer (62.2%). About 30.9% (n = 723) perceived high burden resulting from their relatives' health condition. Logistic analysis showed that women were more likely (OR 1.58, P = 0.0026) and Malays were less likely (OR 0.68, P = 0.0044) to perceive burden. Those who were able to open up to their family or friends (OR 1.65, P = 0.0162) and those who had dysthymia had higher odds (OR 4.91, respectively, P =0.0364) of perceiving burden.


Our results suggest that regardless of the nature of the chronic illnesses, gender or ethnicity, the capacity to open up to family or friends and the mental health status of caregivers can predict their perceived burden. The results provide valuable preliminary information for planning social policies and interventions for improving the well-being of caregivers.
[PubMed - indexed for MEDLINE] 
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 1998 Jun;39(6):251-5.

Studying the Mental Health of a Nation - A Preliminary Report on a Population Survey in Singapore

C S L Fones, E H Kua, T P Ng, S M Ko


Aim: A Singapore Mental Health Survey was designed to study the prevalence and pattern of psychiatric morbidity of the general population. Community surveys reveal the true pattern of mental disorders, free from any self-selection into, or referral within the health care system.

Methods: A cross-sectional survey design was used to estimate the point prevalence of minor psychiatric morbidity (MPM) in an area-probability sample drawn from different regions. Disproportionate quota sampling yielded approximately equal numbers of Chinese, Malays and Indians for inter-ethnic comparison. The General Health Questionnaire, 28-item version (GHQ-28) measured psychoemotional symptoms in 3,020 subjects aged between 13-65 years. The GHQ-28 was validated against ICD-10 psychiatric diagnoses derived from structured psychiatric interview with the Composite International Diagnostic Interview (CIDI).

Results: The optimal cut-off point for the GHQ-28 was determined to be 4/5 for Chinese, and 5/6 for Malays and Indians. Using the validated ethnic-specific cut-offs, MPM rate for Chinese was 17.4%, Malays 15.1% and Indians 17.8%. The population MPM prevalence rate was estimated to be 16.6% after standardisation with population census data. Specific types of ICD-I0 psychiatric disorders which give rise to MPM were mainly anxiety and depressive disorders. Twelve percent of individuals with MPM had at least one ICD-10 disorder in the previous year.

Conclusion: Two-staged methodology is an efficient, cost-effective approach to study population prevalence of mental illness. Screening instruments utilised should be validated specifically for the culture and setting. Information from population surveys of psychiatric morbidity are important for the planning of mental health services for the country.

Keywords: epidemiology, psychiatric morbidity, population prevalence, GHQ


The potentially huge burden of mental ill-health worldwide has been emphasised by the World Health Organisation (WHO) in its report, Investing in Health Research and Development(1). Unipolar depression for example, is predicted to become "the leading cause of disease burden in the developing regions". In order for Singapore and other countries in the region to adequately address the problem of mental ill-health, it is first necessary to ascertain which psychiatric disorders are most prevalent and what its determinants are. 

Studying community samples is especially important, since the majority of people with mental disorder do not seek treatment for their psychological distress(2). Concentrating on clinical populations alone overlooks the many who suffer from the most common psychiatric disorders like depression and anxiety, but who would never otherwise present to a doctor or mental health professional. Indeed, we know from a number of studies that psychiatric disorders are very common in the general population. These are sometimes termed ‘minor’ or ‘neurotic’ disorders, but are known to give rise to significant morbidity, including reduced productivity at work; increased sickness absenteeism and personal disability. The overall poorer quality of life resulting from such psychiatric morbidity is difficult to quantify, but can exact a high societal and personal cost(3).

Studying the general population of a whole nation is however, a large-scale undertaking demanding vast financial and manpower resources; thus, few have been successfully accomplished. Notably, the National Institute of Mental Health, Epidemiological Catchment Area (ECA) surveys(4) and the more recent National Comorbidity Study (NCS)(5) have shaped mental health policy and practice to a great extent in the USA. The OPCS National Psychiatric Morbidity Survey in Great Britain(6) represents yet another large-scale effort to study the prevalence of psychiatric morbidity on a national level. Taiwan’s community survey of minor psychiatric morbidity(7) and the Shatin Community Mental Health Survey in Hong Kong(8) have similarly provided invaluable mental health data in Asian populations. The determinants of mental ill-health have been shown to include a wide variety of social and environmental factors(9,10). Although there is a cross-cultural similarity of symptoms which constitute psychiatric diagnoses(11), symptoms may manifest differently across socio-cultural backgrounds. In a study which compared five Asian sites (Thailand, Indonesia, China, Japan and Taiwan), symptom profiles of neurotic disorders were found to be significantly different(12). Epidemiological findings are unique to a particular population due to differing cultural, socio-demographic, or even biological environments. 

There has been a relative paucity of population-based community surveys of psychiatric morbidity in our region. Bahar et al(13), studied the mental health of Indonesians in Sumatra, while Ramli et al(l4) concentrated on a rural population in Malaysia. In Singapore, population-based epidemiological studies of psychiatric morbidity have been limited to administration of screening instruments to detect emotional symptoms in the community. The Singapore Ministry of Health’s 1978 survey(15) employed the Langner questionnaire and reported that 8.4% had neuroses. The Singapore Association for Mental Health(16) utilised a modified, interviewer administered version of the General Health Questionnaire to estimate psychiatric morbidity in the community and found a rate of MPM of 17.95%. These studies, though providing an indication of how common psycho-emotional symptoms are in the community, have certain shortcomings, principally the lack of validation of the instruments utilised specific for our culture and setting. They also did not study specific psychiatric disorders. 

Our study attempts to fill a crucial gap in available mental health information on Singapore. It employs instruments specifically validated for our population and uses structured psychiatric interview to define operationalised psychiatric diagnoses. We present here, the methodology and preliminary results from this Singapore Mental Health Survey. Our findings and experiences may offer useful lessons for the conduct of future population psychiatric surveys both here and in the region.


A cross-sectional survey design was employed to determine the point prevalence of minor psychiatric morbidity (MPM) in an area-probability sample drawn from different regions in Singapore. Disproportionate stratified quota sampling was employed to obtain approximately equal-sized samples of respondents from the three ethnic groups. Subjects sampled were also stratified by age, comprising adolescents aged 13 - 19 years and adults, 20 - 65 years. 

The frequency and pattern of common psychological symptoms (ie. MPM) in the general population was estimated using the General Health Questionnaire, 28 question version (GHQ-28), a brief, subject-administered (ie. self-rating) questionnaire that measures current non-psychotic, non-organic psychiatric symptoms(17,18). Indices of validity (sensitivity and specificity) of the GHQ may vary considerably, depending on the setting population being studied(19). We thus validated and compared the GHQ-28 among the three major ethnic groups living in Singapore. Three language versions were available - English, Chinese and Malay. Indians in Singapore are usually literate in English or Malay and did not require an Indian-language version. Subjects chose to answer the GHQ in the language version that they were most comfortable with. 

The GHQ-28 was validated against the Composite International Diagnostic Interview (CIDI), a diagnostic instrument developed by the World Health Organisation (WHO) for use in various cultures(20), that assigns operationally defined ICD-10 psychiatric diagnoses. Stratified sampling was conducted of subjects with GHQ scores clustered around the ‘traditional’ cut off of 4/5 points. Selected individuals were contacted by phone and/or letter, visited again in their households and administered the CIDI. Modules of the CIDI detecting the following ICD-10 diagnoses were administered: depressive and dysthymic disorders (F32,33), manic and bipolar affective disorder (F31), phobic and anxiety disorders (F40,41), obsessive compulsive disorder (F42), dissociative and somatoform disorders (F44,45). 

The validity coefficients of sensitivity and specificity were calculated for various GHQ cut-off scores and a receiver operating characteristic (ROC) curve was generated to determine the best cut-off point. Utilising the validated optimal cut-off points for the GHQ, population prevalence of MPM was estimated.

In order to identify which specific diagnostic categories are commonly present as indicated by ‘high’ (above threshold) GHQ scores, one of the 5 sampled regions - Clementi was studied in greater detail. All subjects residing in Clementi who had scored above the GHQ threshold, were interviewed with the CIDI and assigned an ICD-10 diagnosis if present.


Characteristics of respondents

A total of 3,020 subjects were interviewed in the first phase of the study - 1,149 Chinese, 1,024 Malays and 847 Indians. There were 50.4% males and 49.6% females. The age of the sample was relatively young with a mean of 31 years (SD=10.2 years). Table I compares the sociodemographic characteristics of our sample population with the Singapore population(21). In the second validation stage, a sample of 339 subjects (121 Chinese, 112 Malays and 106 Indians) scoring between 1 to 9 points on the GHQ were interviewed with the CIDI.

Validation of the GHQ-28

Comparing the three ethnic group populations, the Chinese had a lower cut-off of 4/5 compared with Malays and Indians who had cut-off levels of 5/6 (Fig 1). For the Singapore general population as a whole, the ‘ideal’ cut-off point was 5/6.

Estimated prevalence of psychiatric disorder

Using the validated GHQ threshold levels, the estimated prevalence of minor psychiatric morbidity in the sample was 17.4% for Chinese, 15.1% for Malays and 17.8% for Indians. For a three races considered together, the estimated prevalence was 16.8%. Direct standardisation for sex, age, and ethnicity (the parameters stratified for in sampling) according to the Singapore population composition(21), showed a similar rate of 16.6%, which is also the population prevalence rate. 

GHQ and specific psychiatric diagnoses

Four hundred respondents were administered the GHQ in the first stage in Clementi, of whom 71 (17.8%) scored above threshold. Of these, 60 were successfully interviewed with the CIDI (response rate of about 85%).

Table II shows the 12-month prevalence rate of specific ICD-10 psychiatric disorders as derived from the CIDI. Affective disorders (7.8%) and anxiety disorders (9.3%) constituted the bulk of psychiatric disorders present in individuals who scored above threshold on the GHQ. Overall, the 12-month prevalence of at least one specific ICD-10 disorder was 12.0%. Of the affective disorders, depressive disorder was the most common (5.5%) and constituted the single most common discrete psychiatric diagnosis. Manic and bipolar disorders were rare.

As a group, phobic and anxiety disorders were more common than depressive disorders. The distribution of discrete anxiety disorder type showed an even spread among panic, social phobia, simple phobia and generalised anxiety disorders. Threshold level somatoform disorders were not common, the commonest being somatoform pain disorder. Co-morbidity was relatively frequent - 7% had two or more threshold level diagnoses.


In epidemiological investigation, it is common to use a screening instrument to identify individuals ‘at-risk’ of having psychiatric disorder, who are then interviewed in detail to diagnose the presence/absence of actual illness(22). Although it would have been ideal to interview all subjects with the CIDI, the cost and resources needed would have been prohibitive. Especially for developing nations in our region, such two-staged or multi-staged methodology is an efficient, cost-effective way to study the prevalence of illness in large populations(23).

Screening instruments however, should be validated for the setting and culture in which it is to be used. We found for example, that Chinese in Singapore have a lower cut-off on the GHQ-28 than Malays and Indians. This may be related to differences in perception, interpretation and expression of psychological distress. Higher GHQ cut-off thresholds have been observed in the more ‘expressive’ cultures, eg. Spain and Italy vs United Kingdom or Iceland, although this has not been consistently demonstrated. Chinese in Singapore may be less expressive of their psychological distress and may be less likely to endorse items on the GHQ even when psychologically ill as compared with Malays and Indians.

Application of different cut-off points, allowed for more accurate inter-ethnic comparisons to be made. If a uniform cut-off point of 5/6 had been applied for the sample overall, the prevalence of psychiatric disorder as estimated by the GHQ-28 would have been 14.7% in Chinese, 15.1% in Malays and 17.6% in Indians. In actual fact, the prevalence, taking into account a lower cut-off of 4/5, makes the prevalence of psychiatric disorder for Chinese 17.4% instead. The prevalence of MPM across ethnic groups was not statistically significant.

The prevalence of minor psychiatric morbidity in Singapore, as estimated by the GHQ-28 was 16.6%. A comparison with other population studies that also used the GHQ to estimate prevalence shows similar levels of psychiatric morbidity in a number of studies. Finlay-Jones & Burvill(24) reported 16.3% of their subjects scoring above threshold. Vazquez-Barquero et al(25)found 18.5%, and Hodiamont et al(26). 22.7% of their study populations who experienced MPM. Verhaak(27) and Goldberg et al(28) reported lower prevalence rates of 12.5% and 11.3% respectively. Our estimated MPM prevalence is comparable with the earlier SAMH study in Singapore utilising the GHQ-28, which reported a MPM of 17.95%(16), but methodological constraints limit valid cross-comparison or analysis of secular trends.

In establishing which specific disorders correspond to a high GHQ score, we identified the common disorders to be affective (7.8%) and anxiety disorders (9.3%). The 12-month prevalence rate for having at least one ICD-10 disorder was 12%. In contrast, the reported one-year prevalence rate of CIDI-derived DSM-III-R disorders in the NCS study(5), which included substance abuse/dependence was 29.5%. In another recent study of adolescents and young adults in Munich, which also utilised the CIDI(29), the 12-month prevalence rate of mental disorders excluding substance-use disorders was 17.5%. Anxiety disorders were the commonest group of disorders followed by affective conditions in the NCS study. Depressive and anxiety disorders were also reported to be the commonest disorders in the Munich study, however depression was more common.

Although the central purpose of psychiatric epidemiology is to guide mental health practice and policy, findings have to be rationally interpreted. Discrepant findings have made cross-comparisons between different epidemiological studies extremely difficult. While the uniform utilisation of standardised highly structured diagnostic instruments like the WHO’s CIDI may limit variations, small changes in diagnostic categories or threshold levels still give rise to large differences in prevalence rates.

Another point of controversy is the ‘high’ prevalence rates reported in most epidemiological studies in the community. Our study for example, indicates that about one out of six individuals in Singapore are deemed to suffer from psychiatric morbidity. Mental health policy makers have to decide how to adequately respond to these individuals with identified ‘morbidity’.

Clearly, experiencing emotional symptoms or even receiving a psychiatric diagnosis is not equivalent to a need for treatment. This is especially due to the fact that epidemiological case identification tends toward diagnosis of milder, ‘borderline’ conditions, for which there is no clear boundary with normality. The Camberwell Needs for Care Survey(30) is important in this regard. Preliminary results have documented that at least 10% of the population were identified as having a need for treatment of a psychiatric condition. Their study of community subjects between 18 - 65 years, utilised similar methodology to our study, including a GHQ-28 screening first stage and second stage psychiatric interview. Their one-year prevalence rate of ICD-10 disorder, of 12.3% was very similar to our result as well. We can thus extrapolate, that the majority of individuals as identified in our study in Singapore are not only experiencing psychiatric symptoms or disorder, but many are also likely to be in need of mental health services.


The key to provision of mental health services of a nation is through well-planned epidemiological research(35). The data obtained from this study provides a good estimate of the extent of psychiatric morbidity in Singapore. Further reports will provide details on the prevalence rates in different sociodemographic groups, life-events and stresses experienced, help-seeking behaviour and service use. These findings will allow us to target population subgroups at increased risk, facilitating prevention, early intervention and treatment of psychological morbidity in the community. There is a need for us in Singapore and the region, to invest adequately in mental health research and development. In so doing, we can do much to ensure a healthy and vital society for ourselves in the future.


This research was supported by a grant from the National Medical Research Council, NMRC/0063/1995.

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