Sex differences in age at first hospital admission for schizophrenia: fact or artifact?

Reports that men develop schizophrenia earlier than women could be a clue to major factors in the pathological processes of schizophrenia or they could be diagnostic artifacts. The authors evaluated the effect of alternative diagnostic systems on age at first admission for schizophrenia, depression, and personality disorder. They found that the age-sex disproportion is specific to schizophrenia and occurs irrespective of the diagnostic system. An unexpected relationship between diagnostic system and sex differences in the rate of schizophrenia obtained, however: the broadest and narrowest sets of criteria yielded approximately equal proportions of females and males, but intermediate systems yielded a significantly greater proportion of males than females.