Schizophrenia Bulletin Advance Access published online on July 21, 2008
Schizophrenia Bulletin, doi:10.1093/schbul/sbn094
Negative Symptoms in Schizophrenia: Avolition and Occam's Razor
2 Centre for Addiction and Mental Health and Department of Psychiatry, Faculty of Medicine
3 Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
1 To whom correspondence should be addressed; Centre for Addiction and Mental Health, 250 College Street, Toronto, ON M5T 1R8; tel: +1 416-535-8501, fax: +1 416-979-4292, e-mail: george_foussias{at}camh.net.
The identification of schizophrenia's negative symptoms dates back to the earliest descriptions of Kraepelin and Bleuler, who each highlighted the central role of avolition in the phenomenology and course of this illness. Since, there have been numerous advances in our understanding of schizophrenia, and the present review tracks the changes that have taken place in our understanding of negative symptoms, their description and measurement. That these symptoms represent a distinct domain of the illness is discussed in the context of their ties to other symptoms and functional outcome. The underlying structure of the negative symptom construct is explored, including several lines of investigation that point towards diminished expression and amotivation as key underlying subdomains. We also discuss findings of intact emotional experience and consummatory pleasure in individuals with schizophrenia, calling into question the presence of anhedonia in this illness. We conclude with a reconceptualization of the negative symptoms, suggesting amotivation (ie, avolition) represents the critical component, particularly in regard to functional outcome. Further exploration and clarification of this core deficit will ultimately enhance our neurobiological understanding of schizophrenia, as well as strategies that may improve outcome.
Keywords: motivation / avolition / apathy / anhedonia / functional outcome / cognitive symptoms