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INTRODUCTION

The designation of mental health by the Commonwealth Government and State and Territory Governments as one of the five National Health Priority Areas is recognition of its social and public health importance. In addition to the pain and disability which may be suffered by individuals, mental illness may also burden their families considerably (Human Rights and Equal Opportunities Commission 1993).

Mental health relates to emotions, thoughts and behaviours. A person with good mental health is generally able to handle day-to-day events and obstacles, work towards important goals, and function effectively in society. However, even minor mental health problems may affect everyday activities to the extent that individuals cannot function as they would wish, or are expected to, within their family and community. Consultation with a health professional may lead to the diagnosis of a mental disorder.

Diagnoses of mental disorders presented in this publication are based on the International Classification of Diseases -10th revision (ICD-10), Classification of Mental and Behavioural Disorders. According to the ICD-10, a mental disorder implies 'the existence of a clinically recognisable set of symptoms or behaviour associated in most cases with distress and with interference with personal functions' (WHO 1992, p. 5).

Background

The economic and personal costs of mental illness are major social and public health issues. In 1992 the Commonwealth Government and State and Territory Governments of Australia endorsed the National Mental Health Strategy (NMHS). These Governments have made a commitment through the NMHS to improve the lives of people with mental illness and of the people who care for them. The strategy aims to:

• promote the mental health of the Australian community;
• where possible, prevent the development of mental health problems and mental disorders;
• reduce the impact of mental disorders on individuals, families and the community; and
• assure the rights of people with mental disorders.

Subsequently, HFS commissioned the Australian Bureau of Statistics (ABS) to conduct the adult component of the survey. Results will assist monitoring initiatives of the NMHS and provide an Australian baseline against which future activity can be compared and evaluated.

Features of adult survey

The 1997 National Survey of Mental Health and Wellbeing of Adults (SMHWB) was conducted from May to August 1997 from a representative sample of persons living in private dwellings in all States and Territories of Australia. At the request of the Health Department of Western Australia, an additional Western Australian survey was conducted from September 1997 to May 1998 in order to increase the total sample. Approximately 5,400 private dwellings were initially selected in the combined Western Australian survey sample. One person aged 18 years or over from each dwelling was subsequently invited to participate. Approximately 4,400 people aged 18 years or over participated in the survey, representing a response rate of 82%. The SMHWB was conducted under the Census and Statistics Act 1905 on a voluntary basis.

The SMHWB was designed to provide information on the prevalence of a range of major mental disorders for Australian adults. The range of mental disorders included in this survey was determined by a Technical Advisory Committee, taking into consideration: disorders that were expected to affect more than 1% of the population; the capacity of the Composite International Diagnostic Interview (CIDI) to diagnose selected mental disorders; and the limitations of a household survey identifying relevant population groups.

Other survey topics included:

• a range of demographic and socioeconomic characteristics;
• physical conditions;
• disability associated with mental disorders;
• health service use for a mental health problem; and
• perceived need for health services for a mental health problem.

To enable the diagnosis of a particular mental disorder, as reported in this publication, the CIDI translates the criteria of the ICD-10 into sets of questions that can be readily answered by the general adult population. The CIDI identifies potential symptoms of mental health problems and probes these symptoms to identify the level of severity (or clinical significance) and eliminates those which are always caused by physical intervention such as drugs, medicines, alcohol, illness or injury. Specific combinations of appropriate symptoms may lead to the diagnosis of a specific mental disorder (e.g. depression). Further details on criteria for mental disorder diagnosis are contained in National Survey of Mental Health and Wellbeing of Adults: Users' Guide, 1997 (ABS Cat. No. 4327.0).

Selected mental disorders

As noted earlier the survey collected information on a range of major mental disorders, but did not attempt to cover all disorders. Prevalence rates for the following mental disorders are presented in this publication:

• Anxiety disorders
• Panic disorder
• Agoraphobia
• Social phobia
• Generalised anxiety disorder
• Obsessive-compulsive disorder
• Post-traumatic stress disorder
• Affective disorders
  • Depression
  • Dysthymia
• Alcohol use disorders
  • Harmful use
  • Dependence
• Drug use disorders

The CIDI is a structured interview for diagnosis of mental disorder for research purposes. The CIDI can inform a clinician's diagnosis but not replace it. Estimates of mental disorders presented in this publication are not clinical diagnoses and are therefore dependent on the accuracy of diagnosis based on survey data.

It is possible that modification of the CIDI, the introduction of ICD-10, and the incorporation of additional modules for the SMHWB may have introduced problems which have not yet been identified. Since the release of the initial publication, Mental Health and Wellbeing: Profile of Adults, Australia, 1997 (ABS Cat. No. 4326.0), it has emerged that the survey instrument did not correctly establish diagnoses of mania, hypomania, and therefore bipolar affective disorder (see paragraph 30 of the Explanatory Notes).

The questions used in this survey to collect data on labour force status and educational qualifications are not precisely the same as those used in other ABS surveys. As such, these data items are not exactly comparable with those in other ABS surveys, but they do provide an indication of an individual's status and they are sufficient to associate with mental health status.

Further information

This publication contains only a selection of the information from this survey. A confidentialised unit record file (CURF) will be available containing a more limited range of variables than provided on the CURF from the national survey. Special tabulations can be produced by the ABS on request - see the advertisement at the back of this publication.


MAIN FINDINGS

Prevalence
Mental disorders

The Human Rights and Equal Opportunity Commission (1993, pp. 908, 925) concluded that people with mental illness are among the most vulnerable and disadvantaged in our community; they may experience stigma and discrimination in many aspects of their lives. Mental illness can be transient; some people experience their illness only once and fully recover. For others, it recurs throughout their lives. For this survey, the prevalence of mental disorders relates to any occurrence of selected disorders during the 12 months prior to the survey. The Western Australian data reveals similar patterns to those in evidence across Australia as a whole (see Mental Health and Wellbeing of Adults, Australia, 1997 (ABS Cat. No. 4326.0)).

Many Western Australian adults enjoy good mental health. Nevertheless, almost one in five (19%) had a mental disorder at some time during the 12 months prior to the survey. The prevalence of mental disorder generally decreased with age. Young adults aged 18-24 years had the highest prevalence of mental disorder (34%), declining steadily to 6% of those aged 65 years and over (see table 2).

Men and women had similar overall prevalence rates of mental disorder. However, from age 25 years women were slightly more likely to have a mental disorder than men (see table 2).

Anxiety disorders include conditions which involve feelings of tension, distress or nervousness, such as post-traumatic stress disorder. The highest rate of anxiety disorders (17%) was observed among women aged 18-24 years. For women, the prevalence of anxiety disorders declined with age to 7% of those aged 65 and over. For men, the prevalence of anxiety disorders was highest (11%) for those aged 45-54 (see table 2). For both men and women, post-traumatic stress disorder and generalised anxiety disorder were the most common anxiety disorders (see table 1).

The prevalence of affective (mood) disorders was highest at 16% for women aged 18-24 years, almost three times the rate for men of this age. For women, the prevalence of affective disorders declined with age while for men, the rate peaked at 7% of those aged 35-44 (see table 2).

Most people with an affective disorder met the criteria for depression (93% of women and 86% of men) (see table 1). People who are depressed lose their enjoyment of life, lack energy and concentration, and may suffer sleep and appetite disturbances.

The survey obtained information on the use of alcohol and four groups of drugs which included both illegal and prescription drugs. Young men were particularly prone to substance use disorders, with almost one in three of those aged 18-24 being affected. For both men and women the prevalence of substance use disorders declined with age to 1.5% of those aged 65 years and over. Alcohol use disorders were more than twice as common as drug use disorders (see tables 1 and 2).

After adjusting for age, the prevalence of mental disorder was highest for men and women living alone (see table 4). Rates of mental disorder were also high among those who were separated or divorced (21% of men and 29% of women). People who had never married also had higher rates of mental disorder than those who were married. Those who were separated or divorced had higher rates of anxiety (15%). Of those never married, 12% had substance use disorders (see table 6).

Education and employment

The Human Rights and Equal Opportunity Commission (1993, pp. 921-4) highlighted a number of factors which, in combination, deny people with mental illness the opportunity to participate in education and employment appropriate to their abilities and interests. Barriers include the debilitating effects of mental illness, a lack of appropriate education services, job design and negative employer attitudes. While people with mental disorders were less likely to have post-school qualifications, and more likely to be unemployed, this reflects a complex interaction of factors. For example, it may be that those with mental disorders find it more difficult to get jobs. At the same time unemployment may contribute to mental disorder.

Those who did not have post-school qualifications were more likely to have a mental disorder than those who did. Some 22% of those who did not complete secondary school, and 22% of those who completed secondary school only, had a mental disorder compared with 16% of those with post-school qualifications.

After adjusting for age, rates of mental disorder were highest for men and women who were unemployed, or not in the labour force. Unemployed people had relatively high rates of affective disorders (13% of men and 18% of women). Unemployed women also had a high rate of anxiety disorders (17%), while unemployed men had a high rate of substance use disorders (20%) (see table 8).

Physical conditions

The survey also collected information on a specific number of chronic and current physical conditions: asthma, chronic bronchitis, anaemia, high blood pressure, heart trouble, arthritis, kidney disease, diabetes, cancer, stomach or duodenal ulcer, chronic gall bladder or liver trouble, hernia or rupture. In every age group women were more likely to report physical conditions than men. Overall 40% of women compared with 33% of men reported physical conditions. The prevalence of physical conditions increased with age from 19% of adults aged 25-34 years to 77% of those aged 65 and over (see table 2).

Comorbidity

Comorbidity refers to the occurrence of more than one disorder at the same time. The existence of some conditions predisposes individuals to others. For example, severe social phobia may cause depression and alcohol dependence. Further, the presence of mental and/or physical conditions in combination is likely to compound the difficulties that people face.

For people with mental disorders, comorbidity is common. For example, one in three of those who had an anxiety disorder also had an affective disorder while one in five also had a substance use disorder. Of those who had an anxiety disorder 9% also had both affective and substance use disorders. This group represents less than 1% of the adult population (see table 12). It should be noted that individuals may have more than one disorder within each of the major groupings. For example, a person categorised as having anxiety disorders may have both social phobia and post-traumatic stress disorder.

Those with affective (mood) disorders were the most likely to also have a mental disorder from at least one of the other major groupings (61%). In comparison, 45% of those with an anxiety disorder also had a mental disorder from one of the other major groupings, as did 30% of those with a substance use disorder (see table 12).

For people with mental disorders the patterns of comorbidity differed for men and women. Women were more likely to have anxiety and affective disorders in combination (19% without substance use disorders and a further 4% with substance use disorders), while men were more likely to have substance use disorders in combination with either anxiety disorders (14%) or affective disorders (10%) (see table 12).

Most people (66%) were designated disability free as measured by the BDQ; 12% had mild, 15% had moderate and 7% had severe disability. Disability increased with age and women were generally more likely to experience disability than men. Of those with a mental disorder, 44% had mild, moderate or severe disability (see table 14 and Appendix 1). They averaged four days out of role in the four weeks prior to interview, compared with one day for those with no mental disorders or physical conditions (see table 15).

The BDQ emphasises physical aspects of disability. Therefore, it is not surprising that according to this measure, physical conditions are more closely related to disability than mental disorders. For example, of those people who reported physical conditions only, 55% had mild, moderate or severe disability status, compared with 36% of those with mental disorders only (see table 14).

Anxiety and affective disorders had a more disabling impact than substance use disorders. Overall, those with anxiety disorders were the most troubled by physical aspects of disability (as measured by the BDQ and SF-12 PCS) (see table 14 and Appendixes 1 and 2), while those with affective disorders fared worst in terms of the SF-12 MCS (see Appendix 2).

Service use

Of those with mental disorders, 39% used a health service for mental health problems in the 12 months prior to interview, with 32% consulting a general practitioner (see table 16). Hospital admissions for mental health problems were rare; less than 1% over the 12-month period.

The likelihood of using health services for a mental health problem was closely related to type of mental disorder. Of those with affective disorders only, approximately 53% used services for mental health problems, compared with 37% of those with anxiety only and 8% of those with substance use disorders only. Those with mental disorders from more than one of the major groupings in combination with physical conditions were the most likely to use services for mental health problems (77%) (see table 16).

A number of those with physical conditions only (9%) or with no mental disorders or physical conditions (6%) used services for mental health problems (see table 16). These groups may have either consulted a health professional for a sub-clinical mental health problem such as stress, or for a mental disorder not included in this analysis such as schizophrenia.