Schizophrenia: still Kraepelin's dementia praecox?

Asking whether E. Kraepelin's early dementia praecox and disease concepts (1896) are still valid today, we condensed his early theory into four theses: 1) schizophrenia is a disease entity, distinguishable from affective psychosis. 2) It is caused by a specific neuropathology. 3) It usually manifests itself in adolescence or early adulthood. 4) Underlying schizophrenia is a progressive disease process that leads to defects and dementia. Having tested whether Kraepelin's dementia praecox and modern schizophrenia are actually comparable, we studied 1) how schizophrenia and depression are linked or separable in terms of symptoms, risk factors and illness course from onset until five years after first treatment contact. The analyses are based on a population-based sample of 130 first admissions because of schizophrenia, 130 age- and sex-matched first admissions because of unipolar depressive disorder and 130 "healthy" population controls from the study area. 2) Results will be presented that, though not very specific, confirm Kraepelin's farsighted hypothesis of a neuropathological basis of the disorder. In this context it will be discussed whether the brain changes are developmental or degenerative in origin. 3) The distribution of age of onset extends far into old age. In a sample of 1109 consecutive first admissions because of nonaffective psychosis from the total age range it was shown that age-dependent developmental factors modify certain components of symptomatology linearly and significantly. The main risk factors, too, significantly change with age. 4) Long-term course was examined in three studies of epidemiologically recruited first-episode samples: Study 1 included five cross sections over 5 years, Study 2 was a prospective pre-post-comparison over 12 years supplemented by a retrospective assessment of the illness course (IRAOS) and Study 3 encompassed 10 cross sections over fifteen years. Finally, the disease concept of schizophrenia, as it presents itself in the light of current knowledge, will be outlined and compared with Kraepelin's earlier and later view of the disorder.