Boundaries of Schizophrenia With other psychiatric illnesses
© Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center 2015.
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Kraepelin’s most influential contribution was the distinction between Dementia Praecox and Manic-Depressive Illness on the basis of a chronic deteriorating vs relapsing-remitting course.11 This evolved into an often debated but relatively unchanged line of demarcation between schizophrenia and bipolar disorder (BPD), espoused by both clinicians and researchers. While earlier family studies largely failed to confirm familial coaggregation of the 2 disorders in general, there were some indications that psychotic BPD overlaps genetically with schizophrenia.12,13 This was supported by linkage studies reporting increased evidence of linkage when psychotic BPD was included in the definition of affection of schizophrenia.14 However, a very large registry-based family study in Sweden reported significantly increased risk of BPD in biological relatives of schizophrenia probands and vice versa.15 The first convincing molecular evidence of genetic overlap was reported by the International Schizophrenia Consortium, which showed that polygenic risk scores