Based on sophisticated clinical descriptions and characteristic symptom patters occurring during the long-term course of psychiatric diseases, Leonhards classification requires that all the clinical features fit for a diagnosis to be made. Always using his own life-long case studies, Leonhard divided the endogenous psychoses into five main nosological groups: on the one hand, the prognostically favourable unipolar affective psychoses, bipolar affective psychoses and cycloid psychoses, and, on the other hand, the prognostically unfavourable unsystematic and systematic schizophrenia. In the meantime, the reliability and validity of this classification have been confirmed by scientific studies and early results provide guidelines for the different origins and varied therapeutic approaches for the specific disease profiles.

No detailed description available for "The Classification of Endogenous Psychoses".

Contradictory results in schizophrenia research are generally explained as being due to genetic heterogeneity and multiple factor heredity in relationship to manifold environmental factors. The book reports a short overview of all relevant twin studies on schizophrenic psychoses and provides data and case histories on a systematic twin study based on a polydiagnostic approach carried out by two independently working psychiatrists. In addition to the internationally applied operational diagnostic systems of DSM-III-R and ICD 10 Leonhard’s subclassification of schizophrenic psychoses was used. Up to now this sophisticated methodological approach is unique in the world. The data provide strong evidence that the spectrum of psychoses with schizophrenic and schizophrenia-like symptoms is not a continuum of diseases. At least in Leonhard’s three major groups of cycloid psychoses, unsystematic schizophrenias and systematic schizophrenias genetic, somatic and psycho-social factors play a completely different etiological role. Cycloid psychoses and systematic schizophrenias are predominantly caused by "environmental” factors. In unsystematic schizophrenias, however, genetic predisposition is the main etiological factor and environmental factors are subordinate.

2013 sees the centenary of Jaspers' foundation of psychopathology as a science with the publication of his magnum opus the Allgemeine Psychopathologie (General Psychopathology), Many of the issues concerning methodology and diagnosis are today the subject of much discussion and debate. This volume brings together leading psychiatrists and philosophers to discuss the impact of this volume, its relevance today, and the legacy it left.

Schizophrenia may not be a single disease, but the result of a diverse set of related conditions. Modern neuroscience is beginning to reveal some of the genetic and environmental underpinnings of schizophrenia; however, an approach less well travelled is to examine the medical disorders that produce symptoms resembling schizophrenia. This book is the first major attempt to bring together the diseases that produce what has been termed 'secondary schizophrenia'. International experts from diverse backgrounds ask the questions: does this medical disorder, or drug, or condition cause psychosis? If yes, does it resemble schizophrenia? What mechanisms form the basis of this relationship? What implications does this understanding have for aetiology and treatment? The answers are a feast for clinicians and researchers of psychosis and schizophrenia. They mark the next step in trying to meet the most important challenge to modern neuroscience – understanding and conquering this most mysterious of human diseases.