Anticipating DSM-V: opportunities and challenges for cognition and psychosis.

The current debate regarding the role that cognitive function should play in the diagnostic criteria for schizophrenia in the DSM-V has been a healthy one that has engendered much useful discussion and potentially interesting pathways for future research. At this point, there is little support for the idea that cognition should be included as a criterion A–type symptom that would differentiate those individuals with schizophrenia from individuals with other psychiatric illnesses. However, there continues to be much interest in including assessments of cognition in the DSM-V as a means of highlighting the importance of cognitive function for understanding functional status and outcome and to facilitate attention to cognitive function in treatment planning. However, as discussed here and in the Bora commentary, these suggestions do raise important theoretical and practical challenges as to how to best accomplish these goals and to provide a means of assessment of cognition that is viable across a wide range of contexts. In order to accomplish these goals, the structure of DSM-V will need to be modified to facilitate the inclusion of treatment-relevant domains that may not be part of the diagnostic criteria such as including assessments of one more domains for all disorders (eg, suicidality and perhaps even cognition) or assessments of domains that may be specific to certain classes of disorders (eg, cognition for psychotic and mood disorders). Bora et al suggest either using specifiers to indicate which individuals with schizophrenia have cognitive impairment or using a dimensional assessment of cognition. We tend to favor a dimensional approach as one that preserves the most information and does not necessitate placing what may be arbitrary thresholds on the level of cognitive dysfunction that would be sufficient to warrant a specifier of cognitive impairment. Furthermore, it is becoming increasingly apparent from the work of Bora and others that cognition may also deserve attention in the assessment of individuals with affective as well as nonaffective psychosis, and thus, whatever approach is adopted in the DSM-V for assessing cognition in schizophrenia may also need to be applicable to individuals with other disorders as well. These are solvable challenges and well worth the effort in terms of their potential payoff for enhancing the quality of life of people with mental illnesses and reducing demands on public health resources.