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63. Stimulus Processing Deficits During Visual Search Following First Psychotic Episode
Background: Impairments in visual processing have previously been documented in psychotic illness. However, their relationship to higher-order disruptions in selective attention remains less well established, particularly early in disease course. The present study examined markers of early visual processing in a first-break psychosis sample (FESz) previously found to exhibit N2pc reductions. Methods: EEG was recorded from 39 FESz and 34 healthy controls (HC) during two visual search tasks that required varying degrees of top-down attentional control, pop-out and serial search. P1 and N1 were largest at PO7/8 electrode sites across groups. Results: While FESz exhibited reduced N1 (p<.01), P1 did not differ between groups,. Larger P1 amplitude was associated with a more robust N2pc among FESz during pop-out (P07: r=-.57, p<.01; PO8: r=-.49, p=.01). There was no association between N1 and N2pc in either group. Discussion: Though P1 was not impaired in our first-episode sample, reduced amplitudes were associated with later disruptions in selective attention as measured by the N2pc. Interestingly, an N1 deficit was present though it did not correlate with N2pc. These findings suggest that sensory-level impairments in visual processing, while better preserved during initial stages of psychotic illness, may contribute to higher-order cognitive deficits observed in psychosis.