Emotion, Motivation, and Reward Processing in Schizophrenia Spectrum Disorders: What We Know and Where We Need to Go

Theorists and researchers on schizophrenia spectrum disorders have long recognized the central role that emotional processing may play in these illnesses since the times of Bleuler and Kraepelin. For example, our current diagnostic criteria for schizophrenia include reference to disturbances in a number of different aspects of emotional processing, including the ability to display affect either facially or vocally, the ability to display emotions that are deemed appropriate to the current context, and the ability to experience or anticipate pleasure. Further, clinicians have long noted the importance of negative mood and depression in understanding function, course, and outcome in this illness. However, despite the centrality of various aspects of emotional processing in several theories of the development of schizophrenia, there is a surprising dearth of empirical work examining emotion and motivation in schizophrenia, particularly when one considers the huge body of work on other aspects of the illness, such as cognition, hallucinations, and delusions. The need for more empirical data in this regard has recently been recognized in a number of initiatives, including an offshoot of theMeasurement and Treatment Research To Improve Cognition in Schizophrenia initiative that has emphasized the importance of more empirical work on negative symptoms in schizophrenia, which include abnormalities in various aspects of emotional and motivational processing. A first question one might ask is why the relative dearth of empirical research on emotion and motivation in schizophrenia? I say relative not only to recognize the work of investigators who have delved into this realm but also to emphasize how little work has been done in an area that so many theories deem highly important to understanding both development and outcome in schizophrenia. One clear reason for the relative lack of empirical research in this area has been the historical notion that emotion ormotivation is somehow hard to study empirically, that it is ‘‘wishy-washy,’’ that it cannot be quantified, and that it is too individualistic or person specific to allow us to draw robust conclusions about processes that might apply to groups of individuals. The massive advances made in affective science and affective neuroscience in the past 20–30 years have helped to dispel these notions and have shown us exactly how we can quantify and empirically study various aspects of emotion andmotivation processing, both at a psychological and a neurobiological level. Further, there is an already large and growing literature on animal models of specific aspects of emotional processing (fear and salience processing), motivation, and reward function that can be brought to bear in trying to understand the neural bases of these processes. Fortunately, for the field of schizophrenia research, a number of investigators are beginning to translate these methods, theories, and concepts into work on schizophrenia, as the reviews in this special issue will illustrate. Another reason for the relative lack of work on emotion and motivation in schizophrenia is the fact that there are actually a number of different processes and mechanisms captured by concepts of emotion and motivation processing, many of which are relevant to understanding schizophrenia. As such, the challenge is not so easy as simply studying ‘‘emotion’’ or ‘‘motivation,’’ but rather to delineate the separable components of these constructs and to make progress in understanding which of these are intact and which are impaired in schizophrenia, what their causal relationships are to each other, and how they may be differentially manifested across the course of the illness or play a role in risk or development. Again, the review articles included in this special issue begin to highlight some of the important distinctions that need to be made among different facets of emotion and motivation processing in psychopathology. For example, the review articles by Kring et al and Philips et al raise important distinctions between (1) the outward display of affect through facial or vocal channels; (2) the experience of emotion in individuals at multiple levels (subjective, To whom correspondence should be addressed; tel: 314-935-8729 or 314-362-2608, fax: 314-935-8790, e-mail: dbarch@artsci.wustl. edu. Schizophrenia Bulletin vol. 34 no. 5 pp. 816–818, 2008 doi:10.1093/schbul/sbn092 Advance Access publication on July 17, 2008