Phenotypic markers as risk factors in schizophrenia: neurocognitive functions

Objective: To review the literature on neurocognitive measures as risk mark ers for schizophrenia and to present data from the Perth family study of sc hizophrenia. Of ail the risk markers that have been identified, the most pr omising are deficits in sustained attention. Method: Inclusion in the review was determined by whether the research addr essed a number of key questions: methods of assessing sustained attention; evidence of sustained attention deficits in patients and first-degree relat ives including children; the importance of attentional dysfunction in the s chizophrenic process and functional outcome; and the biological basis of su stained attention deficits. Results: Sustained attention deficits are evident in both patients and a pr oportion of their first-degree relatives, a finding replicated in prelimina ry data from the Perth family study. The literature suggests that the atten tion deficit is a stable enduring trait that is independent of clinical sta te. The neural basis of the deficit may be a functional disconnection betwe en prefrontal and parietal cortex. Attention impairment is an important pre dictor of functional outcome in patients and the development of social dysf unction in adulthood in the at-risk offspring of patients. However, sustain ed attention deficits that are measured in childhood results in an unaccept able high false-positive rate (21%) when predicting which at-risk offspring of parents with schizophrenia will develop a schizophrenia spectrum disord er, although the overall classification accuracy (78%) is impressive. Conclusions: The main findings are that sustained attention deficits are im portant risk markers for schizophrenia but need to be supplemented by other neurocognitive risk markers to improve predictive accuracy.