The studies of biological markers for genetic vulnerability to schizophrenia, which test an association between a biological measure and schizotypal symptoms, are constrained since these symptoms may lack the specificity for the schizophrenic phenotype. Although family studies of schizophrenic probands validate a familial link between schizophrenia and e schizophrenia spectrum personality (SSPD) traits, the same personality styles may or may not be related to schizophrenia when they occur in an individual who does not have a family history of schizophrenia. Environmental and other genetic factors contribute to the origins of such subtle symptoms in non-familial SSPD individuals. Therefore, an association between a biological measure and these symptoms in the non-- familial SSPD can easily be false (i.e. not related to schizophrenic vulnerability). Such an association can occur for a number of spurious reasons, for instance the symptoms of SSPD themselves may effect the biological measure. In contrast, a strongly deviant finding in the familial SSPD subjects, in the presence of a normal finding (or mildly deviant finding to the extent of the schizophrenic genetic contribution) in the nonfamilial SSPD, makes the biological marker a worthwhile candidate for such investigations. In this case, any spurious association between the phenomena of SSPD and the biological measure can be ruled out. We plan to recruit: familial SSPD subjects (n=30), non-familial SSPD subjects (n=30), and familial (n=30) and non-familial (n=30) controls with no SSPD diagnoses. All groups will be matched on socio-demographic variables. The familial subjects will be recruited from the family members of schizophrenic patients and the non-familial subjects from the community. The following biological measures will be tests to evaluate the psychobiology of SSPD and test putative vulnerability markers: 1) Specific oculomotor measures will be obtained during fixation, smooth pursuit and saccadic tasks. Measures of shift in visual attention independent of eye movements will also be collected through Posner's and specific saccadic eye movement paradigms. 2) Other measures of sustained visual attention in a continuous performance (CPT) will be collected.
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