Assen Jablensky has written a comprehensive and scholarly review of attempts to define valid subtypes of schizophrenia and their implications for genetic research. We are broadly in agreement with the points he makes and the general thrust of his argument, which is that, “The dissection of the syndrome into modular endophenotypes with specific neurocognitive or neurophysiological underpinnings is beginning to be perceived as a promising approach in schizophrenia genetics.” He has, however, misunderstood us if he believes that we (Craddock and Owen, 2005) are advocating replacing the concept of schizophrenia with the pre-Kraepelinian notion of a unitary psychosis. Rather, we believe, like he does, that, “The study of endophenotypes cutting across the conventional diagnostic boundaries may reveal unexpected patterns of associations with symptoms, personality traits, or behavior.”

It is our view that the current diagnostic frameworks are a hindrance to progress in psychiatric research (  Read more

Assen Jablensky has written a comprehensive and scholarly review of attempts to define valid subtypes of schizophrenia and their implications for genetic research. We are broadly in agreement with the points he makes and the general thrust of his argument, which is that, “The dissection of the syndrome into modular endophenotypes with specific neurocognitive or neurophysiological underpinnings is beginning to be perceived as a promising approach in schizophrenia genetics.” He has, however, misunderstood us if he believes that we (Craddock and Owen, 2005) are advocating replacing the concept of schizophrenia with the pre-Kraepelinian notion of a unitary psychosis. Rather, we believe, like he does, that, “The study of endophenotypes cutting across the conventional diagnostic boundaries may reveal unexpected patterns of associations with symptoms, personality traits, or behavior.”

It is our view that the current diagnostic frameworks are a hindrance to progress in psychiatric research (Craddock and Owen, 2005). Jablenksy focuses his review on how best to classify individuals with illness patterns that satisfy definitions of schizophrenia or schizophrenia-like illness. However, we believe it is important to apply the approaches suggested by Jablensky to the full spectrum of mood-psychosis illness; otherwise, we may fail to recognize the close similarity of psychopathology among individuals currently classified in distinct diagnostic groups (Craddock et al., 2006; Craddock et al., 2006). We believe that there should be a move away from nosologists trying to define discrete diagnostic categories in favor of a model of linking dysfunctional biological systems with domains of psychopathology. For this to be realized, we will need to have well-characterized samples of patients that cut across existing nosological categories and a willingness to use novel analytic approaches, such as those discussed by Jablensky.