Mental health of young people in Australia

5 Depressive disorder, conduct disorder and attention-deficit/hyperactivity disorder

Page last updated: October 2000

This chapter reports the prevalence of three mental disorders using the diagnostic framework commonly employed in health services. Parents of children and adolescents aged 6–17 years were administered the Diagnostic Interview Schedule for Children (Version IV) (Shaffer et al., 2000) to identify the prevalence of:

  1. Depressive Disorder,
  2. Conduct Disorder, and
  3. Attention-Deficit/Hyperactivity Disorder (ADHD).
The Diagnostic Interview Schedule uses the criteria described in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, to identify these disorders (American Psychiatric Association, 1994). A brief description of each disorder is shown in table 5.1.

The use of the Diagnostic Interview Schedule for parents to identify three mental disorders may have influenced our prevalence estimates in two ways. First, because parents may not always recognise subjective distress experienced by children and adolescents, it is possible that a higher prevalence of Depressive Disorder may have been identified if interviews had been conducted with the young people themselves. Second, it is possible that some children or adolescents identified as having ADHD may have been more appropriately diagnosed with another disorder not included in the survey. It should also be noted that few children and adolescents were identified with Dysthymic Disorder. For that reason, Dysthymic Disorder and Major Depressive Disorder have been combined in the presentation of results.

Prevalence of mental disorders
Relationships between mental disorders and demographic characteristics
Relationships between mental disorders and health-related quality of life
Comorbidity
Summary
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Table 5.1 Definition of depressive disorder, conduct disorder and attention-deficit/hyperactivity disorder

Table 5.1 is presented as a text in this HTML version for accessibility reasons. It is presented as a table in the PDF version.

Depressive disorder

Children with depressive disorders feel sad, lack interest in activities they previously enjoyed, criticise themselves, and are pessimistic or hopeless about the future. Thinking that life is not worth living, they may contemplate suicide. They may also be irritable and aggressive. They may be indecisive, and have problems concentrating. They tend to lack energy and to have problems sleeping. Major Depressive Disorder is a serious condition characterised by one or more major episodes of depression. A major depressive episode occurs when a child experiences symptoms of depression most of the day, nearly every day, for at least two consecutive weeks. Children with Dysthymic Disorder have less severe symptoms, but their symptoms last for at least a year.

Conduct disorder

Children or adolescents with Conduct Disorder exhibit antisocial behaviour in the following areas:
  1. aggression to people or animals,
  2. destruction of property,
  3. deceitfulness or theft, and
  4. serious violations of rules.
The typical behaviour of those with Conduct Disorder involves bullying, frequent physical fights, deliberate destruction of other people's property, breaking into houses or cars, staying out late at night despite parental prohibitions, running away from home, or frequent truancy from school. To meet DSM-IV criteria for Conduct Disorder, children and adolescents must exhibit three or more of these behaviours during the past 12 months, with at least one behaviour being present during the previous 6 months.

Attention-deficit/hyperactivity disorder (ADHD)

ADHD is defined as a persistent pattern of inattentive behaviour and/or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals of the same developmental level. Children and adolescents with inattentive behaviour problems make careless mistakes with school work, find it hard to persist with tasks and are easily distracted. Those with problems in the area of hyperactivity/impulsivity often fidget and talk excessively, interrupt others, and are constantly 'on the gog. There are three subtypes of ADHD based on the predominant symptom pattern for the past 6 months. Children and adolescents with symptoms of both inattentiveness and hyperactivity-impulsivity are diagnosed with ADHD, Combined Type; those with primarily inattentive symptoms are diagnosed with ADHD, Predominantly Inattentive Type; and those with primarily hyperactivity-impulsivity symptoms are diagnosed with ADHD, Predominantly Hyperactive-Impulsivity Type.

Note. The descriptions in this table are based on the definitions for the disorders in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (American Psychiatric Association, 1994).

Prevalence of mental disorders

Table 5.2 shows the prevalence of the three disorders. The most common disorder was ADHD, which had a prevalence of 11.2%. Within this group, 5.8% had the Inattentive Subtype of ADHD, 2.0% the Hyperactive-Impulsive Subtype and 3.3% the Combined Subtype. The prevalence of Depressive Disorder was 3.7% and that of Conduct Disorder was 3.0% (table 5.2). Males had a higher prevalence of ADHD and Conduct Disorder than did females (table 5.2). There was relatively little difference in the prevalence of Depressive Disorder between males and females in either the younger or older groups (table 5.3).
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Table 5.2 Prevalence (%) of mental disorder

All children & adolescents
%
All children & adolescents
Population estimatea
Male
%
Male
Population estimate
Female
%
Female
Population estimate
Depressive Disorder
3.7
117,000
4.2
68,000
3.2
49,000
Conduct Disorder
3.0
95,000
4.4
71,000
1.6
24,000
ADHD
11.2
355,600
15.4
250,000
6.8
105,000

a estimated number of children and adolescents with a mental health problem in Australia.

Table 5.3 Prevalence (%) of mental disorder by age and gender

6–12 years
Male
6–12 years
Female
13–17 years
Male
13–17 years
Female
Depressive Disorder
3.7
2.1
4.8
4.9
Conduct Disorder
4.8
1.9
3.8
1.0
ADHD
19.3
8.8
10.0
3.8

Note. The impairment criteria required by DSM.IV could not be incorporated into the criteria for a diagnosis used in the survey. It is also possible that for some children their symptoms may have been better accounted for by another mental disorder that was not assessed in the survey.

Relationships between mental disorders and demographic characteristics

With the exception of females with Conduct Disorder, there was a consistent tendency for mental disorders to be more prevalent in step/blended and sole parent families (table 5.4) and in families with the lowest incomes (table 5.5). There was also a general tendency for disorders to be more common in children and adolescents living with parents not in paid employment (table 5.6), a relationship that is consistent with the results reported in chapter 3. Finally, there was a higher prevalence of Conduct Disorder among males living in non-metropolitan regions than in those living in metropolitan regions (table 5.7).
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Table 5.4 Prevalence (%) of mental disorder by family type

Family Type
Original
Family Type
Step/Blended
Family Type
Sole
Males - Depressive Disorder
3.2
6.6
6.1
Males - Conduct Disorder
3.0
9.4
7.3
Males - ADHD
13.2
21.6
20.6
Females - Depressive Disorder
2.0
5.1
8.7
Females - Conduct Disorder
1.3
3.1
1.6
Females - ADHD
5.6
11.8
9.6

Table 5.5 Prevalence (%) of mental disorder by weekly household income

Weekly Income
Less than $580
Weekly Income
$580–$1030
Weekly Income
Greater than $1030
Males - Depressive Disorder
6.5
3.9
2.7
Males - Conduct Disorder
6.9
4.2
2.4
Males - ADHD
19.8
16.2
11.8
Females - Depressive Disorder
9.0
6.0
6.2
Females - Conduct Disorder
1.6
2.3
1.1
Females - ADHD
5.9
1.4
2.2

Table 5.6 Prevalence (%) of mental disorder by parental labour force status

Table 5.6 is separated into 2 smaller tables in this HTML version for accessibility reasons. It is presented as one table in the PDF version.

Two parent households

Disorder
Depressive Disorder
Disorder
Conduct Disorder
Disorder
ADHD110
Males - Both employed
1.9
1.5
12.2
Males - One employed, one not in paid employment
4.6
5.3
14.3
Males - Both not in paid employment
4.3
7.2
18.2
Females - Both employed
1.6
1.6
5.5
Females - One employed, one not in paid employment
2.5
1.1
6.6
Females - Both not in paid employment
3.1
3.2
12.9
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Sole parent households

Disorder
Depressive Disorder
Disorder
Conduct Disorder
Disorder
ADHD
Males - Employed
8.8
6.0
17.9
Males - Not in paid employment
4.5
8.8
23.8
Females - Employed
6.3
0.8
7.2
Females - Not in paid employment
10.9
2.5
11.9

Table 5.7 Prevalence (%) of mental disorder by region

Metropolitan
Males
Metropolitan
Females
Non-Metropolitan
Males
Non-Metropolitan
Females
Depressive Disorder
3.9
3.8
4.6
2.4
Conduct Disorder
3.6
1.8
5.6
1.2
ADHD
14.7
7.1
16.5
6.2

Relationships between mental disorders and health-related quality of life

Parents reported that children and adolescents with Depressive Disorder, Conduct Disorder or ADHD had a lower quality of life in all domains than those without such a disorder (figure 5.1). This pattern was most pronounced in the areas of self-esteem and limitations in peer and school activities related to emotional and behavioural problems. In both these areas, children and adolescents with Depressive Disorder or Conduct Disorder were functioning less well than were those with ADHD.

Children and adolescents with a mental disorder lived in less cohesive families and were perceived by parents to have a larger impact on family activities than those without a disorder (figure 5.2). In both these areas, the relationship was strongest for Conduct Disorder. Parents of children and adolescents with a mental disorder reported a higher level of concern and worry about the health and behaviour of their child or adolescent than did the parents of those without a disorder (figure 5.3). They also reported more limitation in the time available for their personal needs than did the parents of those without a disorder.

It should be noted that the scores for children and adolescents identified as having 'no diagnosis' in figure 5.1, figure 5.2 and figure 5.3 refer to those who did not have any of the disorders assessed in the survey. However, it is likely that some of these children and adolescents did have other mental disorders (e.g., Anxiety Disorders). If these individuals were excluded from the comparison, it is probable that a larger difference would have been found between the quality of life of children and adolescents with no mental disorder and those with one of the mental disorders assessed in this survey.
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Figure 5.1 Health-related quality of life of children and adolescents with a mental disorder


Refer to the following text for a text equivalent of Figure 5.1 Health-related quality of life of children and adolescents with a mental disorder

Text version of Figure 5.1

Figures in this description are approximate as they have been read from the graph.

The figure shows the the average CHQ score (higher is better HRQL, lower is worse HRQL) for children and adolescents with different disorders. The average scores are presented in the following table.
No DiagnosisADHDConduct disorderDepressive disorder
Physical activities
96
94
92
88
Pain & discomfort
88
85
84
76
School/friends - phsycial limitations
96
93
93
88
School/friends - emotional & behavioural limitations
97
82
73
75
Self-esteem
84
71
65
62
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Figure 5.2 Family functioning of children and adolescents with a mental disorder

Refer to the following text for a text equivalent of Figure 5.2 Family functioning of children and adolescents with a mental disorder

Text version of Figure 5.2

Figures in this description are approximate as they have been read from the graph.

The figure shows the the average CHQ score (higher is better functioning, lower is worse functioning) for children and adolescents with different disorders. The average scores are presented in the following table.
No DiagnosisADHDDepressive disorderConduct disorder
Family activities
90
69
64
54
Family cohesion
78
65
62
52
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Figure 5.3 Perceived impact on parents of child and adolescent mental disorders

Refer to the following text for a text equivalent of Figure 5.3 Perceived impact on parents of child and adolescent mental disorders

Text version of Figure 5.3

Figures in this description are approximate as they have been read from the graph.

The figure shows the the average CHQ score (higher is less impact, lower is greater impact) for children and adolescents with different disorders. The average scores are presented in the following table.
No diagnosisADHDDepressive disorderConduct disorder
Emotional impact
85
61
59
56
Time impact
95
78
75
70
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Comorbidity

The presence of more than one mental disorder is described as 'comorbidity'. Figure 5.4 shows the level of comorbidity between disorders. Approximately 23 % of all children and adolescents with one of the three disorders identified in the survey also had symptoms that met the criteria for a second disorder. Overall, males had a higher rate of comorbidity (27%) than females (15%). Less than 1% of children and adolescents met the criteria for all three disorders.

Figure 5.4 Comorbidity of children with Attention-Deficit/Hyperactivity Disorder (ADHD), Conduct Disorder (CD) and Depressive Disorder (DD)


Refer to the following text for a text equivalent of Figure 5.4 Comorbidity of children with Attention-Deficit/Hyperactivity Disorder (ADHD), Conduct Disorder (CD) and Depressive Disorder (DD)
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Text version of Figure 5.4

The figure is a venn diagram of comorbidity of children with Attention-Deficit/Hyperactivity Disorder (ADHD), Conduct Disorder (CD) and Depressive Disorder (DD):
  • No diagnosis - 85.8%
  • Only conduct disorder - 0.9%
  • Only ADHD - 8.3%
  • Only depressive disorder - 1.9%
  • Both depressive disorder and conductive disorder - 0.3%
  • Both conduct disorder and ADHD - 1.3%
  • Both ADHD and depressive disorder - 1.0%
  • All three - 0.5%

Summary

In general, the results reported in this chapter are consistent with those reported in chapter 3. There are several findings of importance. Males in the older and younger groups had a higher prevalence of Conduct Disorder and Attention-Deficit/Hyperactivity Disorder than did females in the same age groups. This pattern is consistent with results reported in several previous studies (Costello et al., 1996; McDermott, 1996). A somewhat surprising result, however, was the relatively small difference between the prevalence of Depressive Disorder in male and female adolescents. A possible explanation for this finding is the focus of the present survey on younger adolescents. Finally, the results from the survey draw attention to the high prevalence of Attention-Deficit/Hyperactivity Disorder among males aged 6 to 12 years.

How should the high prevalence of ADHD identified in this survey be interpreted? We suggest that the high prevalence be viewed with caution because two of the formal criteria identified in the Diagnostic and Statistical Manual, 4th edition (American Psychiatric Association, 1994) could not be incorporated into the assessment of children and adolescents. First, the assessment interview could not determine whether those identified with ADHD met the criteria of having clinically significant impairment in their social, academic or occupational functioning. Second, because the survey focussed on only three disorders it is possible that some of those identified as having ADHD had symptoms which would be better accounted for by another disorder not included in the survey. However, while it seems likely that some reduction in the prevalence estimates for ADHD would have occurred if these criteria had been included, it also seems unlikely that the young people identified with ADHD in the survey were free of problems. Further studies that assess the full range of mental disorders, together with their impact on child and adolescent functioning are needed to more accurately address this issue.

Several demographic characteristics of children and adolescents had an association with child and adolescent mental disorders, much as they did for the mental health problems reported in chapter 3. However, the analyses that examine the prevalence of mental disorders in different demographic groups suggest that the pattern of associations may differ for some disorders experienced by males and females. For example, males living in step/blended families had a higher prevalence of Conduct Disorder than those living in their original families, while females did not show this pattern. These results draw attention to demographic groups in which children and adolescents appear to be at particular risk for mental disorders. The provision of help to these groups should be a priority in programs that aim to reduce the prevalence of child and adolescent mental disorders in the community.

An important finding the extent to which children and adolescents have more than one mental disorder (i.e., comorbidity). The majority of males with Conduct Disorder, for example, also meet the criteria for Attention-Deficit/Hyperactivity Disorder or for Depressive Disorder. These findings highlight the limitation of using a purely categorical approach to describe child and adolescent mental health problems. Furthermore, as noted by Andrews, Henderson, and Hall (2000), most clinical practice guidelines deal with the management of people who have single disorders, whereas in reality many children and adolescents have problems in several different areas. There is a need for clinical guidelines to take more account of this common pattern of problems among young people.
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