Comorbidity of Anxiety and Depression in Children and Adolescents: An Integrative Review

Much evidence exists documenting the comorbidity of anxiety and affective disorders in youth. Furthermore, comorbidity appears to have serious implications both in terms of severity of impairment and course of disorder. Despite this, little is known about the meaning behind the high rate of co-occurrence of anxiety and depression in children and adolescents. Several conditions exist that may give rise to comorbidity. Specifically, two disorders may be comorbid when there is a high rate of symptom overlap between the disorders, when one underlying construct is split into two separate disorders, when the disorders share common risk or etiological factors, or because one disorder causes or increases the risk of developing the second disorder. The present paper examines each of these explanations as they relate to the comorbidity of anxiety and depression in youth.     

Processing Speed Deficits in Attention Deficit/Hyperactivity Disorder and Reading Disability

The goal of the current study was to test whether deficits in processing speed (PS) may be a shared cognitive risk factor in reading disability (RD) and Attention Deficit/Hyperactivity Disorder (ADHD), which are known to be comorbid. Literature on ADHD and RD suggests that deficits on tasks with a speeded component are seen in both of these disorders individually. The current study examined a wide range of speeded tasks in RD, ADHD, comorbid RD+ADHD, and a control group to test whether RD and ADHD have similar profiles of PS deficits, and whether these deficits are shared by the two disorders. The results suggest that a general PS deficit exists in both clinical groups compared to controls, although children with RD demonstrate greater PS deficits than children with ADHD. Two tests (underadditivity and partial correlations) were conducted to test whether these PS deficits are shared. Since we found that PS deficits were underadditive in the comorbid group and that partialling PS reduced the correlation between RD and ADHD, it appears that PS is a shared cognitive risk factor that may help explain the comorbidity of these two disorders.     

Comorbidity and the Treatment of Principal Anxiety Disorders in a Naturalistic Sample

This study examined the impact of comorbidity on treatment outcome and the effects of cognitive behavioral therapy (CBT) for anxiety and depressive disorders on comorbid disorders in a naturalistic sample of 150 patients presenting to an anxiety disorders clinic. The following results were observed across principal (i.e., most severe) diagnoses. Patients with comorbid anxiety and depressive disorders presented for treatment with higher severity of their principal disorder than patients without comorbidity. However, the presence of comorbidity did not predict dropout or poor treatment response, and patients demonstrated significant improvement in their principal disorders regardless of comorbidity. The frequency of clinically severe and subclinical (i.e., not severe enough to meet diagnostic criteria) comorbid conditions decreased significantly over the course of treatment. The implication of these findings for the classification and treatment of emotional disorders is discussed.     

Psychiatric Comorbidity in Children with Autism Spectrum Disorders: A Comparison with Children with ADHD

The present study was conducted with the aim to identify comorbid psychiatric disorders in children with autism spectrum disorders (ASD) (n = 40) and to compare those comorbidity rates to those in children with attention deficit hyperactivity disorder (ADHD) (n = 40). Participants were clinically referred children aged 7–18 years. DSM-IV classifications were used for the primary diagnosis (ASD/ADHD), while comorbid psychiatric disorders were assessed using a structured diagnostic interview, the structured clinical interview for DSM-IV, childhood diagnoses (KID-SCID). Twenty-three children with ASD (57.5 %) had at least one comorbid disorder, whereas 16 children with ADHD (40.0 %) were classified as having at least one comorbid disorder. No group differences were found with respect to this comorbidity rate or for the rate of comorbid externalizing disorders (ODD and/or CD). However, children with ASD had more comorbid internalizing disorders compared to children with ADHD. More specifically, children with ASD had higher rates of anxiety disorders, but not mood disorders. No associations between comorbidity and age or between comorbidity and the intelligence quotient was found. It is important for clinicians to always be aware of, and screen for, comorbidity, and to consider treatment for these comorbid disorders. In addition, research should focus on establishing valid and reliable screening tools as well as effective treatment options for these comorbid disorders.     

Associations Among Anxiety Disorders and Non-anxiety Disorders,Functional Impairment and Medication in Children and Adolescents

This is a study of comorbid anxiety disorders and how they affect the clinical picture of comorbid cases. The sample consisted of 576 Spanish children aged 8 to 17 years receiving psychiatric outpatient consultation that were evaluated using a semi-structured diagnostic interview for both parents and children. A specific association of homotypic comorbidity among anxiety disorders that was independent of the presence of other disorders was found. There was heterotypic comorbidity between anxiety and depressive disorders, ADHD, anorexia and tic disorders. Relationships between non-anxiety disorders were, in general, independent of anxiety, but anxiety moderated the relationship between ADHD-Conduct disorder and Conduct disorder-enuresis. Comorbid anxiety increased difficulties in social interaction, was related with higher global impairment and had an impact on consultation and medication. Anxiety disorder comorbidity should be well recognized in order not to disregard the treatment of all present disorders.     

Perceived causal relations: novel methodology for assessing client attributions about causal associations between variables including symptoms and functional impairment

Researchers have argued that the investigation of causal interrelationships between symptoms may help explain the high comorbidity rate between certain psychiatric disorders. Clients' own attributions concerning the causal interrelationships linking the co-occurrence of their symptoms represent data that may inform their clinical case conceptualization, treatment, and psychological theory regarding the etiology of comorbid disorders. The present study developed and evaluated a novel psychological assessment methodology for measuring Perceived Causal Relations (PCR) and examined its psychometric properties as applied to the question of whether posttraumatic stress and anxiety symptoms represent causal risk factors for depressive symptoms in 225 undergraduates. Participants attributed their symptoms of anxiety and posttraumatic reexperiencing as significant causes of their depressive symptoms. Exploratory analyses identified a listing of symptoms reliably attributed as significant causes of other symptoms and functional impairment, as well as a listing of symptoms reliably attributed as significant effects (outcomes) of other symptoms and functional impairment. The PCR method has promise as an idiographic approach to assessing the causes and consequences of comorbid psychiatric symptoms and associated functional impairment. Research is required to assess the relevance and replicate these findings in distinct psychiatric groups experiencing various symptomatic presentations. Future research may also examine PCR ratings associating other individual differences, for example, between measures of history (e.g., life events), life choices, and personality.     

The developmental mental-disorder histories of adults with posttraumatic stress disorder: a prospective longitudinal birth cohort study

Clinical and epidemiologic studies have established that posttraumatic stress disorder (PTSD) is highly comorbid with other mental disorders. However, such studies have largely relied on adults' retrospective reports to ascertain comorbidity. The authors examined the developmental mental health histories of adults with PTSD using data on mental disorders assessed across the first 3 decades of life among members of the longitudinal Dunedin Multidisciplinary Health and Development Study; 100% of those diagnosed with past-year PTSD and 93.5% of those with lifetime PTSD at age 26 had met criteria for another mental disorder between ages 11 and 21. Most other mental disorders had first onsets by age 15. Of new cases of PTSD arising between ages 26 and 32, 96% had a prior mental disorder and 77% had been diagnosed by age 15. These data suggest PTSD almost always develops in the context of other mental disorders. Research on the etiology of PTSD may benefit from taking lifetime developmental patterns of comorbidity into consideration. Juvenile mental-disorder histories may help indicate which individuals are most likely to develop PTSD in populations at high risk of trauma exposure.     

Distinguishing general and specific personality disorder features and implications for substance dependence comorbidity

Clinical and population-based samples show high comorbidity between Substance Use Disorders (SUDs) and Axis II Personality Disorders (PDs). However, Axis II disorders are frequently comorbid with each other, and existing research has generally failed to distinguish the extent to which SUD/PD comorbidity is general or specific with respect to both specific types of PDs and specific types of SUDs. We sought to determine whether ostensibly specific comorbid substance dependence-Axis II diagnoses (e.g., alcohol use dependence and borderline personality disorder) are reflective of more pervasive or general personality pathology or whether the comorbidity is specific to individual PDs. Face-to-face interview data from Wave 1 and Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions were analyzed. Participants included 34,653 adults living in households in the United States. We used hierarchical factor models to statistically partition general and specific personality disorder dimensions while simultaneously testing for specific PD-substance dependence relations. Results indicated that substance dependence-Axis II comorbidity is characterized by general (pervasive) pathology and by Cluster B PD pathology over and above the relationship to the general PD factor. Further, these relations between PD factors and substance dependence diagnoses appeared to largely account for the comorbidity among substance dependence diagnoses in the younger but not older participants. Our findings suggest that a failure to consider the general PD factor, which we interpret as reflecting interpersonal dysfunction, can lead to potential mischaracterizations of the nature of certain PD and SUD comorbidities.     

Primary prevention of secondary disorders: A proposal and agenda

This paper calls for consideration of a new class of preventive interventions designed explicitly to prevent comorbidity of psychiatric disorders. Epidemiologic data show that successful interventions of this type could be extremely valuable, as up to half of lifetime psychiatric disorders and an even larger percent of chronic and seriously impairing disorders occur to people with a prior history of some other disorder. Furthermore, a review of etiologic hypotheses concerning the causes of comorbidity suggests that interventions aimed at primary prevention of secondary disorders might be feasible. However, more basic risk factor research is needed on the causes of comorbidity before we can make a clear assessment of feasibility and discover promising intervention targets. A number of methodological problems arise in carrying out this type of formative research. These problems are reviewed and suggestions are offered for solutions involving innovations in measurement, design, and data analysis.     

Comorbid attention-deficit/hyperactivity disorder in borderline patients defines an impulsive subtype of borderline personality disorder

In order to examine the impulsive profile of a BPD sample with comorbid ADHD, adult patients who met criteria for BPD were assessed for ADHD with the CAADID and the WURS. A high rate of ADHD in the BPD sample was found, with sixty-nine (38.1%) BPD patients diagnosed as having comorbid adult ADHD. BPD-ADHD group had higher rates of general substance use disorder (59.4% vs. 38.4%), antisocial personality disorder (7.2% vs. 0.9%) and obsessive-compulsive personality disorder (21.7% vs. 6.3%). The BPD group without comorbid adult ADHD showed a higher rate of mood disorders (62.5% vs. 37.7%), panic disorders (54.5% vs. 23.1%) and benzodiazepine abuse (18.8% vs. 5.8%). Only in BPD patients without ADHD was comorbid avoidant personality disorder found. BPD patients could be distinguished in two clear subgroups related to the adult ADHD comorbidity. BPD-ADHD patients showed a more homogeneous and impulsive profile while BPD without ADHD comorbidity had more anxiety and depressive disorders.     

Autismus oder „Psychopathy“?

According to the concept of Hare autism spectrum disorders and psychopathy are associated with a strong deficit in empathy. However, empathy deficits in patients suffering from autism spectrum disorders and empathy deficits in individuals with psychopathic personality traits appear to be different. Some authors described the comorbid occurrence of psychopathic personality traits/psychopathy in individuals with autism spectrum disorders. The following article aims to approach this differential diagnostic problem by a brief review of the literature on a casuistic basis. This article reports the case of a highly remarkable 17-year-old adolescent. The case will be discussed according to the construct of psychopathy with reference to the concept of Hare.     

Neurochemistry in the comorbidity of conduct disorder with other disorders of childhood and adolescence: Implications for counselling

Conduct disorder (CD) is comorbid with other child and adolescent disorders with a frequency that is significantly greater than chance. Findings of studies on neurochemical abnormalities and treatment provide tentative empirical evidence for a neurochemical diathesis in children and adolescents with CD with others disorders. Counsellors of children and adolescents with CD and comorbid conditions with a greater appreciation of the medical and psychosocial aspects of comorbidity are likely to be more effective.     

Basic number processing in children with specific learning disorders: Comorbidity of reading and mathematics disorders

As well as being the hallmark of mathematics disorders, deficits in number processing have also been reported for individuals with reading disorders. The aim of the present study was to investigate separately the components of numerical processing affected in reading and mathematical disorders within the framework of the Triple Code Model. Children with reading disorders (RD), mathematics disorders (MD), comorbid deficits (RD + MD), and typically developing children (TD) were tested on verbal, visual-verbal, and nonverbal number tasks. As expected, children with MD were impaired across a broad range of numerical tasks. In contrast, children with RD were impaired in (visual-)verbal number tasks but showed age-appropriate performance in nonverbal number skills, suggesting their impairments were domain specific and related to their reading difficulties. The comorbid group showed an additive profile of the impairments of the two single-deficit groups. Performance in speeded verbal number tasks was related to rapid automatized naming, a measure of visual-verbal access in the RD but not in the MD group. The results indicate that deficits in number skills are due to different underlying cognitive deficits in children with RD compared to children with MD: a phonological deficit in RD and a deficit in processing numerosities in MD.     

Comorbidity of drug abuse treatment

Research has suggested that comorbidity, the concurrence of substance abuse disorders with other psychiatric disorders, may have prognostic value and important implications for the treatment of substance abuse. Knowledge of the prevalence of comorbid disorder is important because it will enable treatment services to be appropriately configured and designed for clinical drug treatment populations. The form and duration of comorbidity may be influenced by a variety of factors, which include the class of drug being abused, the duration of drug use, the individual sensitivity to drug effects, and whether the drug effects are acute or due to withdrawal or residual conditions. This paper addresses three important scientific questions: (1) What is the prevalence of comorbid disorders in a drug abuser population? (2) What is the stability of psychiatric diagnoses in a drug abuser population? (3) Does the existence of a comorbid disorder influence the outcome of drug abuse treatment?     

Rumination and Excessive Reassurance Seeking: Mediators of the Relationship Between Social Anxiety and Depression?

Social anxiety and depression are highly comorbid conditions. Although this has led researchers to suggest that social anxiety may convey risk for depression, few studies have examined mechanisms of comorbidity between these two conditions. The current study tested two mechanisms of comorbidity between symptoms of these disorders: brooding and excessive reassurance seeking. The data were evaluated in an undergraduate sample assessed three times over a 2 month period. Results suggested that brooding mediated the relationship between social anxiety at Time 1 and depression at Time 3, although no evidence was found for excessive reassurance-seeking as a mediator of these two variables. These findings support recent research suggesting that brooding may be a transdiagnostic process. Theoretical and clinical implications are discussed.     

PTSD,comorbid depression,and the cortisol waking response in victims of intimate partner violence: preliminary evidence

Posttraumatic Stress Disorder (PTSD) and Major Depressive Disorder (MDD) are two highly comorbid and debilitating disorders experienced by more than half of intimate partner violence victims (IPV). Hypothalamic–pituitary–adrenal (HPA) abnormalities are common in both disorders, though the direction of abnormalities often differs. The present study examined the relationship between comorbid PTSD and MDD, and the (salivary) cortisol waking response in 104 recently abused IPV victims. Waking cortisol levels, area under the waking curve with respect to ground (AUCg), and AUC with respect to increase (AUCi) were examined to determine the relation of HPA dynamics to comorbidity for basal versus more dynamic measures. Prior to accounting for comorbidity, women with PTSD or MDD showed significantly greater AUCi than women without the respective disorder. Accounting for comorbidity, PTSD only did not differ from other groups, while MDD only and PTSD + MDD showed greater AUCi than women with neither disorder. Results were nonsignificant for waking cortisol levels or AUCg. Results suggest that MDD drives elevated waking cortisol response, but not basal cortisol activity in recently abused IPV victims. Results demonstrate the importance of examining comorbid diagnoses and HPA activity from a dynamic perspective. Therapeutic implications are discussed.     

Test of Alternative Hypotheses Explaining the Comorbidity Between Attention-Deficit/Hyperactivity Disorder and Conduct Disorder

There is significant comorbidity between attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD). The conclusions of studies that examined the causes of comorbidity between ADHD and CD conflict, with some researchers finding support for the three independent disorders model and others finding support for the correlated risk factors model. We tested these models and eleven alternative hypotheses using the same analytical approach. The participants were 110 monozygotic twin pairs and 181 dizygotic twin pairs recruited from the Colorado Learning Disabilities Research Center Twin Study. The three independent disorders model did not fit the data, whereas the correlated risk factors model fit the data well. Several other comorbidity models fit the data as well as or better than the correlated risk factors model. The results suggest that correlated risk factors are a better explanation for the comorbidity between ADHD and CD than a third, independent ADHD+CD subtype.     

The Comorbidity of Conduct Problems and Depression in Childhood and Adolescence

An extensive body of research documents the high prevalence of comorbidity among child and adolescent disorders in general and between conduct problems and depression in particular. These problems co-occur at significantly higher rates than would be expected by chance and their comorbidity may have significant implications for nosology, treatment, and prognosis. Four main hypotheses have been put forth to account for these high rates of comorbidity. First, comorbidity may be a result of shortcomings associated with referral or informant biases. Second, comorbidity may be an artifact of overlapping definitional criteria. Third, one disorder may cause the other disorder by influencing the developmental trajectory and placing an individual at increased risk for further difficulties. Finally, comorbidity between two disorders may be explained by shared underlying causal or risk factors. The purpose of this review is to explore these possibilities, concentrating primarily on the common risk factors of parent psychopathology, emotion regulation, and cognitive biases that may underlie the co-occurrence of these two disorders. Based on our review, we propose a model for the development of comorbidity between these two disorders.     

Schizophrenia, dissociation, and consciousness

Current thinking suggests that dissociation could be a significant comorbid diagnosis in a proportion of schizophrenic patients with a history of trauma. This potentially may explain the term “schizophrenia” in its original definition by Bleuler, as influenced by his clinical experience and personal view. Additionally, recent findings suggest a partial overlap between dissociative symptoms and the positive symptoms of schizophrenia, which could be explained by inhibitory deficits. In this context, the process of dissociation could serve as an important conceptual framework for understanding schizophrenia, which is supported by current neuroimaging studies and research of corollary discharges. These data indicate that the original conception of “split mind” may be relevant in an updated context. Finally, recent data suggest that the phenomenal aspects of dissociation and conscious disintegration could be related to underlying disruptions of connectivity patterns and neural integration.     

Comorbidity and Internet-Delivered Transdiagnostic Cognitive Behavioural Therapy for Anxiety Disorders

Internet-delivered transdiagnostic anxiety interventions aim to reduce symptoms across several anxiety disorders using one treatment protocol. However, it is unclear whether comorbidity affects outcomes of such treatment. This study re-examined data from a recent randomised controlled trial (N = 129) that evaluated the efficacy of an Internet-delivered transdiagnostic cognitive behavioural therapy (iCBT) intervention for participants with principal diagnoses of generalised anxiety disorder (GAD), social phobia (SP) panic disorder and agoraphobia (PDA), of whom 72% met criteria for a comorbid anxiety disorder or depression. Participants were divided into two groups based on whether or not they had a comorbid disorder before treatment. Participants with comorbid conditions reported higher symptom levels at pre-treatment, post-treatment, and follow-up across a range of measures. Both groups showed significant reductions in symptoms over treatment; however, participants with comorbid disorders showed greater reductions in measures of GAD, PDA, SP, depression, and neuroticism. In addition, treatment significantly reduced the number of comorbid diagnoses at follow-up. These results indicate transdiagnostic iCBT protocols have the potential to reduce comorbidity.