Preliminary communication Deficit status in bipolar disorder: Investigation on prevalence rate and description of seven cases $ Shintaro Nio a, b, n , Takefumi Suzuki a , Hiroyuki Uchida a , Koichiro Watanabe c , Masaru Mimura a a Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan b Department of Psychiatry, Tokyo Musashino Hospital, Tokyo, Japan c Department of Neuropsychiatry, Kyorin University School of Medicine, Tokyo, Japan article info Article history: Received 2 May 2012 Accepted 5 May 2012 Available online 26 July 2012 Keywords: Bipolar disorder Deficit Negative Residual Schizophrenia abstract Objective: While the Kraepelinian dichotomy explicitly distinguishes between schizophrenia and bipolar disorder, it remains unclear as to whether a deficit form of bipolar disorder exists. Method: We conducted a study to investigate the prevalence rate of the deficit form of bipolar disorder; the criteria of which were basically adopted by the original proposal for schizophrenia that described the predominance of negative symptoms for over a year. Moreover, we presented a series of cases with ‘‘deficit’’ bipolar disorder to characterize its clinical pictures in detail. Results: Consecutive outpatients who visited one psychiatric hospital in Tokyo, Japan in March 2007 were evaluated cross-sectionally. Additionally, medical charts of inpatients who were hospitalized in the same hospital between April 2006 and March 2007 were also thoroughly reviewed. Of 494 patients, 7 patients (1.4%; 10.9% of 64 bipolar cases) fulfilled the criteria for bipolar disorder with deficit syndrome. Seven ‘‘deficit’’ cases had a mean 7SD age of 61 75 year-old with the age at onset being 25 78 year-old. In addition to pervasive negative symptoms, they exhibited evidence of cognitive impairments close to the magnitude of what is usually noted in schizophrenia (i.e. a mean 7SD total IQ score of 80 79 in the Wechsler Adult Intelligence Scale and 0.4 70.5 in the Wisconsin Card Sorting Test, categories achieved). Conclusion: Although preliminary, the evidence on deficit status in patients with bipolar disorder that we found in this study appears more consistent with recent evidence and challenges the Kraepelinian dichotomy that reserves deficit status solely to schizophrenia patients. & 2012 Elsevier B.V. All rights reserved. 1. Introduction The Kraepelinian dichotomy has been dominant in modern psychiatry and is based on a clear distinction between schizophrenia and bipolar disorder (or corresponding earlier terms, dementia praecox and manic-depressive illness, respectively) as two major psychotic disorders (Kraepelin and Psychiatrie, 1899). According to Kraepelin, schizophrenia is a disorder with an inevitably progressive course to dementia while bipolar disorder lacks such a deteriorating process. This paradigm has directly affected the two most commonly used operational diagnostic criteria in the field of psychiatry: the Diagnostic and Statistical Manual of Mental Disorders (DSM) (Diagnostic and Statistical Manual of Mental Disorders, 1994) and the International Statistical Classification of Diseases and Related Health Problems (ICD) (International Statistical Classification of Diseases and Related Health Problems Chapter V: Mental and Behavioral Disorders, 1994). Both diagnostic systems put emphasis on pervasive negative symptoms to categorize patients with schizo- phrenia as ‘‘schizophrenia residual type’’ and ‘‘residual schizophre- nia’’ in the DSM and the ICD, respectively, in case they represent a predominant clinical picture. This residual state has been referred to as a deficit form of schizophrenia as defined by Carpenter et al. in 1988. On the other hand, as a growing body of evidence has accumu- lated, the highly influential view on a clear distinction between schizophrenia and bipolar disorder has been challenged. For instance, schizoaffective disorder has been proposed to encompass some key elements in both illnesses (Moller, 2008) and the prognosis for schizoaffective disorder may be intermediate between that of schizophrenia and of bipolar disorder. In fact, both disorders are found to make a spectrum from the viewpoint of long-term outcome (Moller, 2008; Harrow et al., 2000). Furthermore, recent Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jad Journal of Affective Disorders 0165-0327/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jad.2012.05.037 $ This work was presented in a poster session at the 108th annual meeting of the Japanese Society of Psychiatry and Neurology in Kochi, Japan on May 22nd, 2007. n Correspondence to: Department of Neuropsychiatry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Tel.: þ81 3 5363 3829; fax: þ81 3 5379 0187. E-mail address: shin@dd.catv.ne.jp (S. Nio). Journal of Affective Disorders 143 (2012) 248–252