Neurodevelopmental and neurodegenerative hypotheses of schizophrenia: a review and critique

The neurodevelopmental and neurodegenerative hypotheses are current general pathophysiological theories relating to schizophrenia. In this paper, the evidence in support of these theories is presented and critically examined. Strong, but not incontrovertible, evidence supports the neurodevelopmental hypothesis; no direct evidence supports the existence of developmental neuropathology or a neurodevelopmental lesion that causes schizophrenia or its neurodevelopmental abnormalities. On the other hand, the neurodegenerative hypothesis rests on the premise that limited neurodegenerative processes exist. The two theories are not mutually exclusive. The ultimate value of these hypotheses will rest on their ability to stimulate scientific inquiry that leads to discovery of the etiology of schizophrenia.