- One perspective that comorbidity can be examined with is to study how prevalent children meeting diagnostic criteria for anxiety and depressive disorders are
- Costello et al. (1988) reported a low occurrence of comorbidity in a group of pediatric primary care patients at a rate of 0.8% of the sample
- Carey, Finch, and Imm (1989) reported comorbidity rates at 55.2% of children hospitalized with anxiety and depressive disorders, while Kovacs et al. (1989) found a comorbidity rate of 31.5% among outpatient sample
- The difference in rates suggest comorbidity is more common among more "severely disturbed samples"
- Overall, the rates of comorbidity in anxiety and depressive disorders are variable because of confounding factors such as methodological variations in the studies 

Extent of Comorbidity 

- Anxious and depressive symptoms in self report overlap a lot, which indicates that the self-report measure may have low discriminant validity
-  There are two perspectives on this issue: 
- The first perspective believes that the correlations between child and adolescent measures of anxiety and depressive symptoms and the symptom overlap indicates that anxiety and depression are part of a single entity
- The second perspective believes that the issue is item overlap on the actual measures which reflects the shared common symptoms 
- Comorbid depressed and anxious children report higher feelings of depression than children with just anxiety or just depression

Assessment and Measurement Issues

- There is some evidence based on family history and twin studies that indicates there are some familial factors in anxiety and depressive disorders
- Although, some studies have failed to find differences in familial patterns

Familial Factors

- There seems to be temporal relation between anxiety and depression 
- Children with comorbid anxiety and depression tend to be older than anxious-only and depressed-only children. The anxiety symptoms tend to predate the depression symptoms
- Children with diagnosed anxiety disorders do not report many depressive symptoms, while children with diagnosed depressive orders do not report fewer anxiety symptoms

Developmental Differences

- Extent of Comorbidity
- Assessment and Measurement Issues
- Familial Factors 
- Developmental Differences 

Indiana University

The cause of comorbid Anxiety and Depression is debated within the scientific community. Adolescents experience comorbidity of Anxiety and Depression at rates ranging from 15.9%-61.9%.  

Comorbidity of Anxiety and Depression in Youth

Kendall, P. C., Kortlander, E., Chansky, T. E., &amp; Brady, E. U. (1992). Comorbidity of anxiety and depression in youth: Treatment implications. Journal of Consulting and Clinical Psychology, 60(6), 869–880. https://doi.org/10.1037/0022-006x.60.6.869 

Comorbidity of Anxiety and Depression in Youth: Treatment Implications

There are theoretical and definitional issues with the comorbidity of Anxiety and Depression such as: 
- Symptoms Versus Syndromes
- Single Construct: Negative Affectivity
- Temporality
- Heterogeneity

Theoretical and Definitional Issues

Review of Comorbidity Data

It is important to review the treatments of depression and anxiety separately before we can study how they may interact together. 

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