• comorbidity;
  • psychiatric disorders;
  • disease

Lilienfeld et al's critique of the use of the term comorbid in psychopathological research is critically examined. They are incorrect in asserting that the original use of the term in medical epidemiology was intended to restrict it to disease entities. Furthermore, the ways in which medical comorbidity can be understood apply equally well to understanding the comorbidity of psychiatric or psychological disorders. Just as it has been useful to use the general term psychiatric disorders to include symptom patterns and syndromes and few If any true diseases, so to it is useful to apply the generic term of comorbidity to the joint occurrence of psychiatric disorders. Because methodological factors can sometimes contribute to artifactual comorbidity which is uninformative about the disorders being studied is no reason to abandon the term comorbidity in psycho-pathological research.