Discrete and continuous approach in the conceptualization of bipolar disorder and schizophrenia

Validity of the current diagnostic distinction of bipolar affective disorder and schizophrenia in classification systems ICD-10 and DSM IV is challenged by an accumulating amount of various independent findings. The authors review the similarities and distinctions beetween both disorders in a range from psychopathology to neuroimaging methods. An emphasis is given on genetic findings as a major source of evidence of an overlap between bipolar disorder and schizophrenia. Presumably, a combination of common genetic factors with additional genetic and other illness-unique factors is necessary for development of either disorder.