Is distress a symptom of mental disorders, a marker of impairment, both or neither?

In discussing the virtues of disentangling assessments of functional impairment from the diagnostic criteria for mental disorders, Üstün and Kennedy have not considered “distress” – a concept without any clear definitional boundaries that is, nevertheless, used widely in the DSM system and, to a lesser extent, in the ICD system.

In the majority of cases, distress is matched with functional impairment: DSM-IV criteria for most depressive disorders, anxiety disorders, personality disorders, sleep disorders, somatoform disorders and some other disorders require the presence of either functional impairment or “clinically significant distress” (in some diagnoses labeled as “marked distress”), and ICD-10 criteria for several diagnoses (e.g., obsessive-compulsive disorder (OCD), hypochondriasis, sleep disorders, personality disorders) also require either functional impairment or distress. Assuming it will be possible to convince clinicians and researchers to carve out functional impairment from diagnostic criteria – a process that will be more traumatic for some disorders than others – a subsequent problem will be to decide what to do with “distress” in the proposed integrated DSM-ICD diagnostic schemata. The options include jettisoning the concept entirely, making distress a required stand-alone symptom for these disorders, or integrating distress into the assessment of functional impairment.

Some writers 1, 2 argue that distress is a transient phenomenon related to specific stressors that subsides when the stressor disappears or as the individual adapts to the stressor. However, if the experience of distress is far in excess of what is culturally appropriate or persists well after the termination of the primary (or secondary) stressor, then it is considered part of a pathological psychological process and should be seen as a marker of a mental disorder 1. These authors argue that failure to discriminate these two situations leads to medicalization of normal responses to stress 2, 3. However, reliably making this distinction between “normal” and maladaptive distress can often be quite difficult, because it requires detailed information about the stressors affecting the individual and about “appropriate” responses to such stressors for persons of the same age, gender and educational level in the individual’s socio-cultural environment.

The DSM-IV attempts to eschew social causation of symptoms (with a few notable exceptions, such as post-traumatic stress disorder and adjustment disorder), so there are no criteria for determining when distress becomes “clinically significant”. In practice, this usually hinges on an assessment of the degree of impairment produced by the distress, not on the “inappropriateness” of the distress. Based on this conceptualization of distress, the danger of medicalization of normal responses, the difficulty of discriminating normal and maladaptive distress, and the probable substantial overlap between functional impairment and “clinically significant distress” as operationalized in the DSM, suggest that little would be lost if the term “distress” was completely removed from the diagnostic criteria.

Other authors 4 argue that distress is an underlying component of anxiety and depression that is not transient and not normal, an interpretation that is more consonant with the usage of distress in the DSM and ICD systems. But there are substantial differences in the treatment of distress between the two diagnostic systems, and inconsistencies in the use of distress between different diagnoses within each system. In DSM-IV distress is an important indicator of the severity of depressive disorders (co-equal with functional impairment), but in ICD-10 distress is not considered in the diagnosis of depressive disorders (other than as one of the “non-diagnostic symptoms” for other depressive episodes). In the DSM-IV criteria for phobias and OCD, distress is both a marker of severity (co-equal with impairment) and given equal status with anxiety as a cardinal characteristic of the core symptoms (e.g., the recurrent thoughts of OCD must cause “marked anxiety or distress”); in ICD-10 “emotional distress” is a required, stand-alone symptom for phobias (not matched with impairment) and a marker of severity of OCD (co-equal with impairment), but is not mentioned as a characteristic of the core symptoms of either phobias or OCD. In the ICD-10 criteria for somatoform disorder, “persistent distress” leads to repeated care-seeking but this is not mentioned in the DSM-IV criteria. Separation anxiety disorder must include “recurrent excessive distress” (DSM-IV) or “excessive, recurrent distress” (ICD-10) about separation.

These examples show that both diagnostic systems use distress as a stand-alone symptom, as a qualifier of other symptoms and as a general measure of severity; but neither the DSM-IV nor the ICD-10 provides a definition of the term, so there can be a wide range of interpretations of the corresponding diagnostic criteria. The frequent use of various qualifiers for distress in the diagnostic criteria (“clinically significant”, “marked”, “excessive”, etc.) suggests that distress is construed as a dimensional construct that is being truncated to be employed as a categorical diagnostic criterion, but the diagnostic systems do not assess the degree of distress and do not provide further clarification about the cut-off between distress that is and is not diagnostically important.

The potential removal of functional impairment from the diagnostic criteria brings the non-specific and inconsistent usage of distress in DSM-IV and ICD-10 into a much clearer focus, because the most common current usage of distress is as a co-equal measure of severity with functional impairment. There have been a wide range of definitions of distress in the literature 4, but there is still no general consensus and it is unlikely that one will emerge in the foreseeable future. Thus, if DSM-V and ICD-11 intend to maintain the term, an unambiguous operational definition that clearly distinguishes distress from depression and anxiety needs to be included in the glossary, and a method for rating the severity of distress must be developed.

If it is not possible to develop a unique, non-overlapping operational definition of distress, I would recommend dropping distress entirely from the diagnostic criteria and from the assessment of functional impairment. If it is possible to develop such a definition, I would recommend using distress as one of the dimensional components of the functional impairment assessment for all disorders (i.e., not part of the diagnostic criteria) and, perhaps, as a required or optional symptom for some specific diagnoses.