Original Research
Phenomenology and Comorbidity of Dysthymic Disorder in 100 Consecutively Referred Children and Adolescents: Beyond DSM-IV
Gabriele Masi, MD1, Stefania Millepiedi, MD1, Maria Mucci, MD1, Rosa Rita Pascale, MD1, Giulio Perugi, MD2, Hagop S Akiskal, MD3
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Objective: Diagnostic criteria and nosological boundaries of juvenile dysthymic disorder (DD) are under-researched. Two different sets of diagnostic criteria are still discussed in the DSM-IV, the first giving major weight to somatic and vegetative symptoms and the second, included in the appendix, to more affective and cognitive symptoms. The aim of this study was to describe prototypical symptomatology and comorbidity of DD, according to DSM-IV criteria, in a consecutive series of referred children and adolescents, as a function of age and sex.
Method: One hundred inpatients and outpatients (36 children and 64 adolescents, 57 males, 43 females, age range 7 to 18 years, mean age 13.3 years) received a diagnosis of DD without comorbid major depressive disorder (MDD), using historical information, the Diagnostic Interview for Children and Adolescents-Revised (DICA-R), and symptoms ratings according to the DSM-IV criteria.
Results: Irritability, low self-esteem, fatigue or loss of energy, depressed mood, guilt, concentration difficulties, anhedonia, and hopelessness were present in more than 50% of subjects. Differences in symptomatic profile between male and female patients were not significant. Anxiety disorders were commonly comorbid with DD, mainly generalized anxiety disorder, simple phobias, and in prepuberal children, separation anxiety disorder. Externalizing disorders were reported in 35% of the patients, with higher prevalence in male patients. Adolescents showed more suicidal thoughts and anhedonia than children.
Conclusions: The clinical picture of early-onset DD we found, based entirely on a pure sample without current and past MDD, is not totally congruent with the diagnostic criteria according to DSM-IV. A more precise definition of the clinical picture may help early diagnosis and prevention of superimposed mental disorders.
(Can J Psychiatry 2003;48:99–105)
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Clinical Implications
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Some of the symptoms reported in the alternative DSM-IV research diagnostic criteria for dysthymia are particularly frequent. At least for juvenile DD, DSM-IV diagnostic criteria may be inappropriate.
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Comorbidity with anxiety disorders is particularly frequent.
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“Mixed” bipolar elements (irritability, psychomotor agitation, concentration difficulties) are present in a relevant proportion of cases, and they confirm that, in a significant minority, early-onset DD belongs to the bipolar spectrum.
Limitations
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This was a retrospective evaluation of lifetime comorbidity.
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Findings on symptomatology and comorbidity will only apply to patients and cannot be regarded as valid for nonreferred populations.
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Reliability of both children’s and parents’ recall of previous episodes is poor.
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Key Words: dysthymic disorder, depression, DSM-IV, children, adolescents
Résumé : Phénoménologie et comorbidité du trouble dysthymique chez 100 enfants et adolescents dirigés consécutivement : au-delà du DSM-IV
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Dysthymic disorder (DD) is a fluctuating chronic depressive disorder, characterized in children and adolescents by a minimum duration of 1 year, according to the DSM-IV (1). In clinical samples the duration typically exceeds that given in DSM-IV; that is, a mean of 3.9 years (2). Symptoms frequently begin early in life (3,4), with insidious onset, and pursue a protracted course resulting in significant functional impairment (5,6). This could distort character formation and lead to interpersonal difficulties (7). Early onset is considered to be a predictor of poorer outcome, in terms of increased vulnerability to other mood disorders (major depressive disorder, [MDD] and bipolar disorder) (8,9), as well as to other internalizing or externalizing disorders (10–13). Many issues in dysthymia still remain uncertain, such as its prototypical clinical picture. DSM-IV (1) suggested 2 alternative diagnostic criteria: the first gives major weight to somatic and vegetative symptoms (altered appetite, disturbed sleep, low energy, or fatigue), and the second derives from the DSM-IV mood disorder field trial, with more affective and cognitive symptoms (low self-esteem, feelings of hopelessness, loss of interest, social withdrawal, low energy or fatigue, feelings of guilt, feelings of irritability, decrease of activity, and difficulty in thinking). According to the DSM-IV, additional confirmatory evidence is needed for this second version.
Another uncertain topic relates to the nosological boundaries and comorbidity of DD with MDD (14,15) and with anxiety disorders (10,16,17). From 42% (9,18) to 75% (6) of children and adolescents with DD have a superimposed MDD (“double depression”). The comorbidity with anxiety disorder ranges from 11% (19) to 55% (15), and with externalizing disorders, it ranges from 20% (20) to 100% (14). Differences in sampling (community vs clinical studies, the latter including inpatients and outpatients and including children and adolescents), as well as in classification (some studies include DD and double depression in the same category, labeled as “chronic depression”), may account for these wide differences (14).
The aim of the present study is to describe symptomatology and comorbidity of DD in a large sample of consecutively referred children and adolescents. To delineate a specific profile of depressive symptomatology in “pure” DD, all subjects with current or previous MDD (double depression) were excluded.
Methods
Sample
All the patients between the ages of 7 and 18 years who were referred to our Division as inpatients (n = 73) or outpatients (n = 197) were screened for psychiatric disorders in the same structured way, including historical information, a clinical interview, the Diagnostic Interview for Children and Adolescents-Revised (DICA-R) (21), and symptoms ratings according to the DSM-IV criteria. Our clinic is a tertiary level research hospital with a national catchment for children and adolescents with a wide range of neuropsychiatric disorders. The children were referred by other hospitals, community-based child psychiatrists or pediaticians, or family members. All subjects with psychosis or mental retardation, as well as subjects with poor verbal skills (expression and comprehension) were also excluded. From these patients, a consecutive series of 100 children and adolescents (57 males and 43 females, 74 outpatients and 26 inpatients, age range 7 to 18 years, mean age 13.3 years, SD 3.0), constituting 37% of the entire population of mentally ill children and adolescents referred to our center, received a current diagnosis of DD without current or previous MDD, according to DSM-IV diagnostic criteria. The high rates of patients with DD may be accounted for by the frequent referral for childhood mood and anxiety disorders, since our research group particularly specializes in this field. No patient with DD was using psychotropic drugs during assessment. The patients were divided by age into children (36 subjects, 21 males and 15 females, age range 7 to 11 years, mean age 10.2 years, SD 1.0) and adolescents (64 subjects, 36 males and 28 females, age range 12 to 18 years, mean age 15.0 years, SD 2.0). Sociodemographic variables were assessed by the parents’ education and occupation, according to the Hollingshead’s 2-factor index (22). All subjects were in the middle to upper-middle socioeconomic classes. Socioeconomic status distribution (highest vs middle categories) and family structure (intact vs monoparental families) did not differ between groups (males–females and children–adolescents). All subjects and their families participated in the study after informed consent was obtained. The characteristics of the assessing instruments and the aims of the study were explained to the subjects and their parents. The study was approved by the Human Subjects Committee of our hospital.
Measures
The DICA-R was administered individually to the children and adolescents participating in the study and to their parents by separate interviewers. The DICA-R is a structured interview according to DSM-IV, organized in such a way as to explore the presence or absence of each of the symptoms in different psychiatric syndromes. Three trained child psychiatrists administered the clinical interview. The comprehension of the questions was carefully assessed; if necessary, the questions were repeated to clarify the subject’s response. All subjects participating in the study were considered competent to undergo the diagnostic interview. Child and parent ratings correlated in the moderate-to-high range on measures of children’s symptoms. To improve the reliability and validity of the diagnosis, clinical data from each subject–parent pair were reviewed by the research clinicians after each interview to arrive at consensus. When questions arose, patients and parents were reassessed for further clarification. Structured interview diagnoses were considered positive only if DSM-IV criteria were unequivocally met. When an overlap of symptoms among different concurrent disorders was found, particularly between DD and generalized anxiety disorder (GAD), an operational methodology described by Kovacs and coworkers (8,10) was followed to decide whether the symptom belonged to one or another disorder. Symptoms were considered manifestations of DD only if symptoms had clearly started with the onset of the depression. If such symptoms were quantitatively and qualitatively the same as before the onset of depression, they were considered as correlates of GAD only but not of the depressive disorder. In all cases, the final diagnoses depended on the clinicians’ symptom ratings.
In the depressive and anxiety sections of DICA-R, 15 items corresponding to depressive symptoms were selected: depressed mood, irritability, pathological guilt, anhedonia, fatigue, concentration difficulties, psychomotor agitation, psychomotor retardation, insomnia, hypersomnia, increased appetite, reduced appetite, death thoughts, low self-concept, and hopelessness.
Our previous analyses of children and adolescents assessed with DICA-R revealed a good interrater reliability for the diagnosis of DD, as well as for the identification of particular symptoms (K > 0.75) (23). The individual reliability for the specific items, that is, the property of each question to obtain the same answer when the item is reformulated, was good for all the items.
Statistical Analyses
Descriptive analyses were used. To identify differences among subjects an independent sample t-test or an analysis of variance (ANOVA) was used with the number of symptoms as the within-subject values, and age and sex as among-subject variables. Chi-square analyses were performed on categorical variables (for example, presence or absence of symptoms and comorbid diagnoses). In comparisons with small expected cell frequencies, Fisher’s exact tests were performed. All tests were 2-tailed; statistical significance was set at 5% level (P < 0.05). Bonferroni correction was applied where necessary, to minimize type I errors.
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