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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).
In developing the strategy it was recognised that there was a lack of adequate mental health research and data on the prevalence of mental disorders and the welfare of mentally ill people in the community. In December 1994 a workshop commissioned by the then Commonwealth Department of Health and Family Services (HFS) recommended the conduct of a national survey of mental health and wellbeing to meet this need. The survey was to comprise three components: an adult study; a child and adolescent study; and a study of low prevalence (psychotic) disorders, such as schizophrenia.
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.
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:
Measuring mental health
Measuring mental health in the community through household surveys is a complex task, as mental disorder is usually determined through clinical diagnoses. For the SMHWB the diagnostic component of the interview was administered through a modified version of the CIDI. This is a comprehensive interview for adults which can be used to assess current and lifetime prevalence of mental disorders through the measurement of symptoms and their impact on day-to-day activities. The World Health Organisation Training and Reference Centre for CIDI in Australia, contracted by the then HFS, developed a computerised version of the CIDI for the SMHWB.
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).
The survey instrument also incorporates additional CIDI modules which provide a set of screening questions for other mental disorders such as personality disorders. These modules provide an indication of whether a disorder may be present. However, they do not collect sufficient information to determine whether the criteria for a diagnosis of a mental disorder by the CIDI are met. As a diagnosis for these mental disorders is not made, the overall prevalence rates of mental disorder presented in this publication may underestimate the extent of mental disorder in Western Australia.
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.
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).
Types of mental disorders
While men and women had similar overall prevalence rates there were differences by type of mental disorder. Women were about twice as likely as men to have experienced anxiety disorders (13% compared with 7%) and affective disorders (9% compared with 4%). On the other hand, men were more than twice as likely as women to have substance use disorders (13% compared with 5%) (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).
Because mental disorder is age-related, when examining the effect of factors such as household size, marital status and labour force status (all of which are also age-related) it is useful to adjust the data to control for age. This is done by calculating age standardised prevalence rates. For further information see paragraphs 35-37 of the Explanatory Notes.
Mental illness can have a disruptive influence in personal relationships. Sometimes the stigma and ignorance surrounding mental disorder lead to isolation. A lack of social contact can be as damaging and painful as the disorder itself. The burden of care borne by the families of those affected by mental disorder places pressure on family relationships, and can contribute to family breakdown (Human Rights and Equal Opportunity Commission 1993, pp. 455, 468-9, 474) .
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).
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).
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).
Those with anxiety or affective disorders were more likely to report physical conditions (39% and 40% respectively) than Western Australian adults on average (36%). Men with either anxiety or affective disorders were more likely to report physical conditions (44% and 46% respectively) than their female counterparts (37% and 38% respectively). On the other hand, women with substance use disorders were more likely to report physical conditions than their male counterparts (39% compared with 34%) (see table 12). People who had mental disorders from all three groupings concurrently were the most likely to report physical conditions (46%) (see table 12).
The survey used a number of different measures of disability, based on standard international questionnaires, in order to measure the impact of mental disorders and physical conditions on people's lives. The Brief Disability Questionnaire (BDQ) asks respondents if they are limited because of health problems in a number of activities, and if they have cut down or stopped activities they were expected to do as part of their routine. The Short Form 12 (SF-12) is designed to measure the physical and mental aspects of health separately by addressing limitations due to health across eight dimensions. In addition, respondents were asked how many days in the four weeks prior to interview they were unable to carry out usual activities fully (days out of role).
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).
The SF-12 has two measures, the physical component summary (PCS) and the mental component summary (MCS). The PCS focuses mainly on limitations in physical functioning, role limitations due to physical health problems, bodily pain and general health. The MCS focuses mainly on role limitations due to emotional problems, social functioning, mental health and vitality. A higher score indicates better health. As expected, persons with physical conditions only scored lower on the PCS than average, but higher on the MCS, while the pattern was reversed for those with mental disorders only (see Appendix 2).
Combinations of disorders generally have a cumulative effect on disability. Those with anxiety, affective or a combination of mental disorders from more than one of the major groupings (anxiety, affective and substance use) in combination with physical conditions were the worst affected. Of those with mental disorders from more than one of the major groupings in combination with physical conditions, 9% had mild, 36% moderate and 20% severe disability according to the BDQ (see table 14). They were among the lowest scoring on both SF-12 measures (see Appendix 2) and reported the highest number of days out of role, an average 7.6 days out of the four weeks prior to the interview (see table 15).
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).
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.
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