Contagion in schizophrenia: a critique of Crow and Done (1986)

This article discusses the literature on the possible role of viruses in the development of schizophrenia and outlines the evidence that compelled Crow and Done (1986) to reject a horizontal contagion hypothesis (e.g., sibling to sibling transmission). We posit a genetically determined age after which one becomes vulnerable to the illness, rather than a strict age of onset. We also propose an environmentally determined range of resistance to this susceptibility as an alternative conceptualization of the role of inheritance and of viral exposure in the etiology of the disease. The predictions derived from our new model fit the findings of Crow and Done and are consistent with the older literature of possible viral factors, thus reaffirming the horizontal contagion hypothesis.