Purpose of review: Following the recent progress mainly in the fields of genetics and neurobiology, the validity of the diagnostic distinction between schizophrenia and bipolar disorder is increasingly challenged.
Recent findings: Evidence for basic neurobiological processes common for both disorders is expanding with regard to (a) susceptibility genes, (b) neurodevelopment (for example myelination), and (c) brain functions (for example sensory gating, visuospatial achievement). Recent epidemiological studies also stress communalities.
Summary: The diagnostic split between schizophrenia and bipolar disorder is unable to define distinct etiological and/or pathophysiological entities.