background We still do not know how genetic and environmental factors cause schizophrenia. The pathogenesis of this illness is unknown.
aim To develop a pathogenetic model that has greater explanatory power than the existing hypotheses concerning schizophrenia.
method We searched the literature with the help of Medline (from 1966) using the search terms 'schizophrenia', 'basal ganglia', 'striatum' and 'cerebellum'. We also consulted recent manuals on schizophrenia, evolutionary psychiatry and neuroanatomy
results The analysis showed that during the phylogenesis and ontogenesis of the brain two mechanisms, which are primarily motor-control mechanisms, are applied to the intentional level of functioning; one of these initiates and delivers power to intentions (the drive mechanism), whereas the other steers and guides intentions (the guidance mechanism). As a result of the repeated application of these two mechanisms an imbalance to the detriment of the drive mechanism in the end manifests itself as schizophrenia. The model clarifies the clinical and epidemiological findings and the course of the illness.
conclusion The model provides a more comprehensive explanation for existing clinical and epidemiological data than do current alternatives. The model is compliable with the main prevailing views of psychiatrists on schizophrenia and it places the genesis of schizophrenia in an evolutionary perspective.