Conduct Disorder (CD) has long been observed to be frequently comorbid with depression,1,2
giving rise to a number of differing explanatory models. Rutter and colleagues (1970; as cited in Puig-Antich, 1982)3
described 21% of the children in the Isle of Wight study as “mixed” in terms of conduct and emotional problems, noting that they were more similar to children with CD than depression. However, others4
described the behavioral problems shown by those with comorbid depression and conduct problems as “soft core” behavioral problems, and described their comorbidity as “masked depression,” implying that the primary difficulties for the child were symptoms of depression.4
Some have suggested that the comorbidity between CD and depression should be classified as a distinct diagnostic entity altogether.3
Although such a diagnostic category has not been included in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV),5
Depressive Conduct Disorder has been identified as a separate disorder in the International Classification of Diseases (ICD-10).6
The evidence for distinguishing such a disorder separately from Major Depressive Disorder and CD is not clear.
How the disorders typically develop may provide important information about the nature and implications of their comorbidity. If conduct problems act as a mask for underlying depression, it might be expected that depression symptoms tend to precede behavioral problems, and there is some support for this.7
However, other evidence suggests that CD precedes depression, and further that negative life events associated with CD may mediate the links between CD and depression.8-9
Oppositional Defiant Disorder (ODD), on the other hand, temporally precedes both CD and Depression,8, 10-11
and is also commonly comorbid with both.1-2
Because Oppositional Defiant Disorder (ODD) temporally precedes both CD and depression, and is commonly comorbid with both, an alternative model of the comorbidity of the latter two conditions is that ODD may represent a common early precursor condition. An examination of the developmental comorbidity among boys in a clinic-referred sample found that, over 10 assessment waves, ODD symptoms predicted depression symptoms in the following year.8
In contrast, after accounting for ODD and for negative life events, CD symptoms were no longer predictive of depression. Similar results were found in a community sample of boys and girls;9
after accounting for negative life events, delinquency was not predictive of depression, whereas oppositionality showed a direct relationship with later depression. ODD in adolescence has also been found to predict depression in adulthood.12
Attempting to clarify the nature of the links between ODD and depression, Burke13
postulated that specific features of ODD may help to explain these direct links. Factor analyses using a clinic-referred sample of boys, the Developmental Trends Study (DTS), suggested that ODD symptoms loaded on two dimensions: negative affect and oppositional behavior. Negative affect consisted of the symptoms touchy, angry
, and spiteful
. The symptoms of loses temper, defies
loaded onto a separate factor of oppositional behavior. The symptoms annoys others
and blames others
were not consistently associated with either factor. When these symptoms were summed to create separate constructs, negative affect symptoms predicted depression, whereas oppositional behavior predicted later CD symptoms. Thus, not only were there distinct dimensions, but they were specific in their prediction of later psychopathology in a homotypic fashion. It is possible that negative affective symptoms of ODD explain the previously observed comorbidity between CD and depression. If so, negative affective symptoms might also serve as an early precursor to later internalizing psychopathology, and may provide important information about the risks for comorbidity among children with ODD or CD.
This finding has implications beyond whether and why the comorbidity of ODD and depression explains observed links between CD and depression. Negative affective symptoms of ODD may highlight important distinctions among children with ODD in terms of course, prognosis and risk for comorbid conditions. They may also indicate links between early temperament and childhood psychopathology. Recently, Stringaris and Goodman14
examined similar ad hoc
ODD dimensions. However, notable differences were the inclusion of loses temper
on the affective dimension, and moving spiteful and vindictive
to a separate third dimension. Consistent with the findings from the DTS, their affective dimension predicted later emotional psychopathology, but in contrast all three dimensions predicted later CD, including the affective dimension.14
Mick and colleagues15
examined a construct of irritability created of the symptoms of loses temper
– thus identical to that of Stringaris & Goodman.14
In Mick and colleagues15
study however, irritability was not associated with increased risk for later mood disorder.
Some discussion has been given to the question of whether and how girls might differ from boys in the manner in which they manifest conduct problems. Boys meet criteria for CD at much higher rates, and show higher levels of physical aggression than girls.16-18
Girls have been speculated to engage in more socially directed aggression,19-21
although recent evidence finds no gender difference in the rate of relational aggression (Keenan, Coyne & Lahey, 2008).22
Aggressive boys are more likely than girls to become involved in delinquency and violent crime.23
On the other hand, although rates of ODD are higher among boys than girls in childhood, girls show rates equal to boys by adolescence.10
Some have speculated that discrepant prevalence rates observed for CD may be due to the symptoms by which conduct problems are assessed. If so, it may be hypothesize that the mechanisms of comorbidity between ODD and CD and depression might differ for girls.
Likewise, girls show higher rates of depression than boys, as well as showing a different course of depression symptoms over time. From early adolescence the gender ratio for depression increases greatly, when girls' rates begin to exceed those for boys'. 16, 24-27
As a result, the developmental associations between depression and other disorders may be anticipated to differ between girls and boys.
Finally, previous examination of negative affective symptoms of ODD13
has been conducted using a clinic-referred sample of boys alone. Such a sample would be expected to represent more extreme levels of antisocial behavior. The observed relationship between negative affective symptoms of ODD and depression in that sample may therefore also differ for a community sample. Berkson's bias,28
a selection bias associated with the increased likelihood that individuals in a sample drawn from a hospitalized population will show more than one disease condition, should be absent in a community sample. This may be especially relevant for studies of ODD and CD, since it appears that rates of CD without ODD differ markedly between community and clinical samples.13
The present study sought to replicate prior findings13
within a large community sample of girls, the Pittsburgh Girls Study. Based on previous findings, we hypothesize that factor analyses of ODD symptoms would show two underlying dimensions, a negative affective dimension consisting of being angry, touchy and spiteful, and a behavioral dimension of losing temper, arguing and defying. We hypothesize that the negative affective, but not the behavioral, dimension would predict levels of depression. In contrast, we expected that the behavioral, but not the negative affective, dimension would predict CD symptoms. We hypothesize that this relationship would not change with increasing age. Finally we hypothesize that these relationships would hold up even when controlling for other commonly comorbid psychopathology (Attention Deficit Hyperactivity Disorder (ADHD) and anxiety), as well as family and demographic covariates.