Psychiatric comorbidity: fact or artifact?

Abstract

The frequent occurrence of comorbidity has brought about an extensive theoretical debate in psychiatry. Why are the rates of psychiatric comorbidity so high and what are their implications for the ontological and epistemological status of comorbid psychiatric diseases? Current explanations focus either on classification choices or on causal ties between disorders. Based on empirical and philosophical arguments, we propose a conventionalist interpretation of psychiatric comorbidity instead. We argue that a conventionalist approach fits well with research and clinical practice and resolves two problems for psychiatric diseases: experimenter’s regress and arbitrariness.

Psychiatric Comorbidity Does Not Only Depend on Diagnostic Thresholds: An Illustration With Major Depressive Disorder and Generalized Anxiety Disorder

“…Comorbidity patterns are not independent of classification systems, nor completely determined by or an artifact of these systems. [15] The findings of this study should be interpreted in light of several strengths and limitations. On the other hand, rates of comorbidity depend on the actual occurrence of these symptom combinations in the population.…”

“…Thus, comorbidity rates might be best understood from a position in between a constructivist and realist stance. [15] The findings of this study should be interpreted in light of several strengths and limitations. First, the prevalence rates of MDD, GAD, and comorbidity naturally depend on the time frame in which they were measured.…”

“…From this "constructivist" interpretation it follows that comorbidity is not a reflection of different co-occurring disorders that are causally connected. However, based on findings of a previous study on comorbidity among a limited selection of psychiatric symptoms, [15] we hypothesize that rates of comorbidity will not always fluctuate when diagnostic thresholds are adjusted. [6] Although several studies have hypothesized about the influence of classification choices on rates of comorbidity among DSM disorders, no previous studies have systematically tested these hypotheses in empirical data.…”

“…[8,14] For these reasons, rates of comorbidity among these two disorders would be expected to be particularly highly dependent on classification choices. However, based on findings of a previous study on comorbidity among a limited selection of psychiatric symptoms, [15] we hypothesize that rates of comorbidity will not always fluctuate when diagnostic thresholds are adjusted. To investigate this, we studied whether different threshold levels of MDD or GAD affect rates of comorbidity in order to clarify the origins of comorbidity.…”

Beyond bioethics: the 5th International Philosophy of Medicine Roundtable

“…Hanna van Loo and Jan-Willem Romeijn, in ''Psychiatric Comorbidity: Fact or Artifact?'' [16], ask why comorbidity is so high for psychiatric conditions. Often, a depressed patient is also anxious, a schizophrenic patient also depressed.…”