Neurological soft signs in adolescents with poor performance on the continous performance test: markers of liability for schizophrenia spectrum disorders?

There is much evidence that neurological soft signs (NSS) are highly prevalent in both adults and children with schizophrenia. In addition, they have been detected as early precursors of a schizophrenic outcome in at-risk subjects. Such findings point to the possible value of NSS as neurointegrative markers in schizophrenia which has been hypothesized to be a neurodevelopmental disease. In our study we used a biobehavioral criterion to select the 'at-risk' group, a sustained attentional deficit as measured by the continuous performance test (CPT). We compared 140 normal adolescents with 162 'CPT-linked vulnerable' adolescents (index subjects) on a battery for the assessment of NSS (including laterality), IQ, frontal lobe function and schizotypy. An association was found between NSS and attentional deficit. Furthermore, index subjects with NSS were characterized by lower IQ scores, poorer performance on frontal lobe tests and greater problems with social interaction. There was also a trend for an association between male sex and both left-handedness and NSS.